How to be an Engine Expert on MGs - Mg-tabc.org

<strong>How</strong> <strong>to</strong> <strong>be</strong> <strong>an</strong><strong>Engine</strong> <strong>Expert</strong> on MGsMG <strong>Engine</strong>s from 1935 <strong>to</strong> 1998Neil Cairns

<strong>Engine</strong>s for M.G.sTheir S<strong>to</strong>ry after 1935by Neil CairnsCopyright Neil Cairns • Decem<strong>be</strong>r1997Edition 2 • ammended 26.09.981

Covering the XPAG seriesBMC ‘A’ SeriesBMC ‘B’ SeriesWith their relative units such as the Twin Cam,BMC ‘C’ series, Rover V8, some early Morris units, the‘O’, ‘R’, ‘S’ <strong>an</strong>d ‘K’ series till 1998A study of engines fitted <strong>to</strong> MG carsfrom 1935 <strong>to</strong> 1998The cover Pho<strong>to</strong> is that of a K1 Magnette, using a derivate of the Wolsley Hornet <strong>Engine</strong>. The engines in thisbook are those made after such wonderful pieces of equipment.2

M.G. <strong>Engine</strong>s1935–1998Of all the engines M.G. used, perhaps the most rom<strong>an</strong>tic is the XPAG shown <strong>be</strong>low,as it powered the majority of the ‘T’ type Midgets, on their spindly wheels with flowingwings. The version <strong>be</strong>low is the unit destined for the M.G. ‘One <strong>an</strong>d a Quarter Litre’saloon of 1947, the huge air silencer above the engine <strong>an</strong>d its single SU H2 carburet<strong>to</strong>r<strong>be</strong>ing identifying signs, with its early oil filter.3

ContentsIntroduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5An <strong>Engine</strong> . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7Chapter One, M.G. <strong>Engine</strong>s Care of Morris . . . . . . . . . 8Chapter Two, The TA Onwards . . . . . . . . . . . . . . . . . . 12Chapter Three, ‘X’ Series of <strong>Engine</strong>s. . . . . . . . . . . . . . . 25Chapter Four, XPAG State of the Art . . . . . . . . . . . . . . 46Chapter Five, BMC ‘A’ Series & Triumph . . . . . . . . . . 56Chapter Six, BMC ‘B’ Series . . . . . . . . . . . . . . . . . . . . . . 84Chapter Seven, Big ‘B’ Series . . . . . . . . . . . . . . . . . . . . 112Chapter Eight, ‘C’, & ‘K’ series, & Rover V8’s . . . . . 121Chapter Nine, Rover ‘O’, ‘R’, & ‘S’ Series . . . . . . . . . 138Chapter Ten, Gearboxes <strong>an</strong>d Axles . . . . . . . . . . . . . . 145Chapter Eleven, Conclusions . . . . . . . . . . . . . . . . . . . 148Index <strong>to</strong> Chapters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 150Picture Credits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 152“Remem<strong>be</strong>r, all <strong>an</strong> engine does is push a car along“Anon.FOREWORD & BIBLOGRAPHY.4

With such excellent books on M.G. his<strong>to</strong>ry about, it would <strong>be</strong> utterly pointlesstrying <strong>to</strong> retell it all. If that is what you are after, then obtain ‘M.G. by McComb’, ‘Magicof the Marque’, ‘McComb, Maintaining the Breed’, all by F. Wilson McComb; ‘Tuning<strong>an</strong>d Maintenace of MG’s’ by Phillip H. Smith; ‘The Magic of MG’ , ‘MG, Magic of theMarque’ by Mike Allison; <strong>an</strong>d ‘MG The Un<strong>to</strong>ld S<strong>to</strong>ry’ by David Knowles. Once youhave absor<strong>be</strong>d these, you are <strong>an</strong> ‘expert’. This book is a collection of information <strong>an</strong>ds<strong>to</strong>ries I have collected over about 20 years, with obvious reference <strong>to</strong> MG his<strong>to</strong>rybooks. It is not a workshop m<strong>an</strong>ual, even though there are hints <strong>an</strong>d tips fromexperience of working on them, on the XPAG, ‘A’, ‘B’ & ‘C’ series, <strong>an</strong>d the V8, all ofwhich I have owned <strong>an</strong>d run for a num<strong>be</strong>r of years, ( especially the XPAG <strong>an</strong>d ‘B’.) It isnot a his<strong>to</strong>ry book, even though the chapters <strong>an</strong>d models are in order. It is <strong>an</strong>information book for <strong>an</strong> enthusiast by <strong>an</strong> enthusiast, who saw something somewhereabout M.G. engines, <strong>an</strong>d needs it all in one book. The political infighting, <strong>an</strong>d hardcommercialism of production <strong>an</strong>d profits does not interest me, so I have deli<strong>be</strong>ratelyavoided it. Within these pages is information <strong>an</strong>d my views, about the engines thatM.G. used after the comp<strong>an</strong>y had come under firm control of Morris Mo<strong>to</strong>rs Ltd.Other reference matter, some read a long time ago I might add, was ‘M.G. Cars’, byC.P. Davidson;’The Book of the Austin A40', by Ellison Hawks; ‘Wolseley Cars’ <strong>an</strong>d‘Morris <strong>Engine</strong>s’, by D.V.W. Fr<strong>an</strong>cis; ‘BMC ‘B’ Series’ by Lindsay Porter; ‘Tuning the ‘A’Series’, by David Vizard; ‘Post War Baby Austins’, by Barry Sharratt; ‘Morris Bullnose& Flatnose’, by Peter J. Seymour; ‘Y type Saloons & Tourers’ by John Lawson; ‘TheMorris S<strong>to</strong>ry’, by Bri<strong>an</strong> Whittle, ‘The Rover S<strong>to</strong>ry’ <strong>an</strong>d ‘Triumph Spitfire’ by GrahamRobson; ‘British Leyl<strong>an</strong>d’, by Jeff D<strong>an</strong>iels; ‘The Breakdown of Austin Rover’, byWilliams, Williams & Haslam; ‘’Metro’, by Mark Steward; ‘Lord Nuffield’, by PeterHull; ‘The Private Mo<strong>to</strong>r Car’, a collection of the Cromp<strong>to</strong>n-L<strong>an</strong>chester Lectures <strong>to</strong> theIME in 1960; <strong>an</strong>d m<strong>an</strong>y, m<strong>an</strong>y road tests found in the ‘Brookl<strong>an</strong>ds Books’ collection,from ‘Au<strong>to</strong>car’, ‘Mo<strong>to</strong>r’, ‘the Light Car’; articles in the MGCC magazine ‘Safety Fast’;articles in the MGOC magazine ‘ Enjoying MG’; articles in the MG Octagon CCmagazine, ‘Bulletin’; my own experiences since 1960, <strong>an</strong>d items that I have forgottenfrom whence they came.**Note that this IS NOT <strong>an</strong> engine tuning book.NC.Quote: “In more th<strong>an</strong> 60 years there have <strong>be</strong>en m<strong>an</strong>y M.G.s, some of them remarkably goodcars <strong>an</strong>d some of them really very bad, but the vast majority have <strong>be</strong>en honest in design <strong>an</strong>dexecution.“This includes their engines, of course.F.W. Wilson McComb. 1984**A special th<strong>an</strong>kyou must go <strong>to</strong> Malcolm Taylor of the MGOCC, <strong>an</strong>d John Lawsonof the ‘Y’ Register, for their help with this rather involved book.5

<strong>Engine</strong>s for M.G.s(From the TA <strong>to</strong> the MGB)(1935 <strong>to</strong> 1990)IntroductionThere are lots of pretty M.G. books about, full of excellent pho<strong>to</strong>graphs <strong>an</strong>d text,that gloss over import<strong>an</strong>t technical parts, or simply do not mention them. Others go<strong>to</strong>o deep <strong>an</strong>d lose the reader in a morass of figures <strong>an</strong>d graphs. The simple aim of thisbook is <strong>to</strong> get round the difficulty of finding out that odd bit of information you knowyou saw somewhere. The mech<strong>an</strong>ical components of <strong>an</strong> M.G. such as its engine, has <strong>to</strong><strong>be</strong> looked at with the view that after 1935 M.G. used <strong>an</strong>d developed Morris, <strong>an</strong>d later,BMC/BL, then Rover, parts for their own use. Some enthusiasts either forget, or choose<strong>to</strong> ignore this.The excellent engine drawings included are those of Mo<strong>to</strong>r, Au<strong>to</strong>car, Sphere, <strong>an</strong>dLight Car magazine technical artists, <strong>an</strong>d are shown as <strong>an</strong> ‘art’ of their times. This is nota his<strong>to</strong>rical epistle, nor is it a life s<strong>to</strong>ry of M.G., but if you like engines, <strong>an</strong>d those ofM.G. cars in particular, <strong>an</strong>d their roots, read on.6

ENGINES for M.G.sAn <strong>Engine</strong>Do you remem<strong>be</strong>r the first time you ever started up a cars engine? The fact that itstarted just <strong>be</strong>cause you pushed a but<strong>to</strong>n, pulled a knob, or turned a key? Your Dadscar perhaps, in the garage, or on the drive, when he was not about. It burst in<strong>to</strong> lifefrom its coma<strong>to</strong>se state, <strong>an</strong>d you heard the noise <strong>an</strong>d felt its power through the seat <strong>an</strong>dyour foot on the accelera<strong>to</strong>r. Then there was the day you actually first drove a car, or inmy case a small Ferguson trac<strong>to</strong>r. This thing with <strong>an</strong> engine in it, the feeling of power, itscared you that you would have <strong>to</strong> control this energy. The feeling you had as the carlurched forward, assuming you chose first gear! It did not take long <strong>to</strong> <strong>be</strong> able <strong>to</strong>control the engine, you quickly learned how <strong>to</strong> use a clutch <strong>an</strong>d accelera<strong>to</strong>r, thenhopefully, the brakes. That feeling you had, is it still there?Today’s cars are just bits of technology <strong>to</strong> use, from A <strong>to</strong> B. Their reliability ismarvellous, but there is no fun <strong>an</strong>ymore. The risks <strong>an</strong>d excitement has gone. To start up<strong>an</strong> engine in <strong>an</strong> old M.G. is <strong>to</strong> recapture that first thrill, <strong>to</strong> feel you w<strong>an</strong>t <strong>to</strong> control it.This is true of <strong>an</strong>y old car of course, but M.G. does fire the imagination. M.G. are afterall only ‘Safe <strong>an</strong>d Fast’ cars that rely on well proven parts from others, <strong>be</strong> it eitherMorris or later BMC/BL. They are not super-fast cars, nor very large, nor expensivewhen made, ( though some c<strong>an</strong> <strong>be</strong> <strong>to</strong>day as people try <strong>to</strong> recapture their youth.....................or that first thrill.) Ancient bits of hot steel <strong>an</strong>d aluminium spinning,reciprocating, vibrating, <strong>an</strong>d producing power, under your control.It matters not which model you drive, leave the worrying over whether it is a ‘realM.G.’ <strong>to</strong> others, the thrill is there in <strong>an</strong>y M.G. saloon or sportscar.We are a very lucky generation, in that we have the mo<strong>to</strong>r car for pleasure. It c<strong>an</strong>notcontinue forever, let us enjoy them whilst we c<strong>an</strong>. Let us now look under the bonnet<strong>an</strong>d find out about the engines s<strong>to</strong>ry, why it is there, where it came from, <strong>an</strong>d <strong>to</strong> whomit is related. <strong>Engine</strong>s from Austin, Morris, Triumph, <strong>an</strong>d Rover were fitted <strong>to</strong> M.G’sover the years. An old saying goes that Morris are cars that s<strong>to</strong>p but do not go, <strong>an</strong>dAustin are cars that go but do not s<strong>to</strong>p, a reference <strong>to</strong> the immediate pre-war pairscompeti<strong>to</strong>rs models; one had good brakes, the other good engines. They were <strong>to</strong> joinforces as the British Mo<strong>to</strong>r Corporation, ( BMC,) after the war, in 1952, then BritishLeyl<strong>an</strong>d, (BL), in 1968, then the Rover Group in 1986.7

Chapter OneM.G. <strong>Engine</strong>s, Care of Morris (1935 <strong>to</strong> 1955)The Pre-War <strong>an</strong>d Immediate Post War EraThe internal combustion engine ( ICE,) has now <strong>be</strong>en with us for some considerabletime, <strong>an</strong>d it must now <strong>be</strong> under the bonnets of millions upon millions of vehiclesworldwide. The M.G. mo<strong>to</strong>r car comes in<strong>to</strong> the picture in approximately 1923/24,evolved by Cecil Kim<strong>be</strong>r, in the early days of the Au<strong>to</strong>mobile. The engines used <strong>be</strong>forethen were purchased from outside the main Morris Comp<strong>an</strong>y, but as the Morris empiregrew <strong>an</strong>d grew, so he <strong>be</strong>g<strong>an</strong> <strong>to</strong> buy up his suppliers. The comp<strong>an</strong>y of Hotchkiss inGosford Street, Coventry were purchased in 1923 <strong>to</strong> <strong>be</strong> renamed Morris <strong>Engine</strong>sBr<strong>an</strong>ch. They supplied Morris with the engines for the later model of the Bull Nose (<strong>an</strong>d M.G.) saloon cars. Hotchkiss et Cie had moved <strong>to</strong> the United Kingdom fromFr<strong>an</strong>ce in WW1 <strong>to</strong> escape the Germ<strong>an</strong>s, <strong>to</strong> continue making armaments, <strong>an</strong>d carried onusing their original machine <strong>to</strong>ols <strong>an</strong>d equipment. They had never made <strong>an</strong> engineuntil they met William Morris, but had excellent machine shop facilities <strong>an</strong>d a veryexperienced workforce, <strong>an</strong>d were looking about for work after the war.The machinery <strong>an</strong>d <strong>to</strong>ols had come over from Fr<strong>an</strong>ce, <strong>an</strong>d this included the threadcutting dies <strong>an</strong>d taps used on their guns. These threads of <strong>an</strong> unusual French Metricsize were used up until 1956 in the last ‘X’ series engine in the Wolseley 4/44, having<strong>be</strong>en used in virtually all Morris <strong>an</strong>d M.G. engines till then. These metric threads arenot quite the same as those used <strong>to</strong>day. The last M.G. <strong>to</strong> use such threads was theTF1500 in 1955. Such nuts <strong>an</strong>d bolts have British BSW/BSF head sizes, so that theaverage British DIY owner or mo<strong>to</strong>r mech<strong>an</strong>ics <strong>to</strong>ol kit could still <strong>be</strong> used, but withthese odd metric threads. From then on, starting with the M.G. ‘Z’ Magnette in 1953,Austin engines were used under the umbrella of the British Mo<strong>to</strong>r Corporation, orBMC for short. These BMC engines used Americ<strong>an</strong> based Unified Fine (UNF) <strong>an</strong>dcourse (UNC) threads, ( ANF & ANC in the USA,) in the ‘A’,’B’ <strong>an</strong>d ‘C’ series M.G.used. Such nuts <strong>an</strong>d bolt heads had <strong>to</strong> <strong>be</strong> used with sp<strong>an</strong>ners that are termed “A/F”,indicating the dist<strong>an</strong>ce Across the Flats, a common size for inst<strong>an</strong>ce,<strong>be</strong>ing 1/2" AF.Later still, st<strong>an</strong>dardised ISO metric sizes <strong>to</strong>ok over with the ‘A’ Plus, ‘O’,’R’,’S’, <strong>an</strong>d ‘K’series engines of Austin/Rover.Other items used with the Morris engine were made by outside contrac<strong>to</strong>rs, <strong>an</strong>dthey <strong>to</strong>o were taken over one by one, so that Os<strong>be</strong>r<strong>to</strong>n Radia<strong>to</strong>rs <strong>be</strong>came MorrisRadia<strong>to</strong>rs in 1922 as Morris was their only cus<strong>to</strong>mer. Skinners Union who made SUcarburetters for Morris were purchased in 1926. The next year the first M.G. fac<strong>to</strong>rywas built at Cowley, <strong>an</strong>d then M.G. moved <strong>to</strong> Abingdon in 1929.The Hotchkiss ‘side valve’ (sv) <strong>an</strong>d Morris/Wolseley ‘overhead camshaft’ (ohc)engines used by M.G. <strong>be</strong>fore WW2 are well documented. This book is about those usedby M.G. from 1935/36 when M.G. <strong>be</strong>came part of The Nuffield Org<strong>an</strong>isation, from thelittle TA Midget right up <strong>to</strong> the latest Rover/M.G. MGF sportscar.Like all things, a car engine is a compromise. It would <strong>be</strong> nice <strong>to</strong> <strong>be</strong> able <strong>to</strong> use the<strong>be</strong>st materials, <strong>an</strong>d h<strong>an</strong>d assemble the accurately machined components <strong>to</strong> the ‘BluePrint’. A blue print is a ‘working copy’ of the drawing of the engine from the designoffice. They were blue <strong>be</strong>cause of the method of copying such large drawings in those8

days. In reality the m<strong>an</strong>ufacturer has <strong>to</strong> use metals that are cheap, hard wearing, willmachine easily, <strong>an</strong>d take up complicated cast shapes. The engine must <strong>be</strong> designed for<strong>an</strong> assembly line as well as a long life. As M.G. was originally a small part of a hugemo<strong>to</strong>r m<strong>an</strong>ufacturer, Morris, they were limited <strong>to</strong> using parts that were available fromthe huge corporate parts bin. As a mass produced component for millions of cars, <strong>an</strong>engine has <strong>to</strong> have <strong>to</strong>ler<strong>an</strong>ces, me<strong>an</strong>ing that a cylinder bore will <strong>be</strong> <strong>be</strong>tween two sizes,the variation often <strong>be</strong>tween two-thous<strong>an</strong>dths of <strong>an</strong> inch, ( 0.002"), <strong>an</strong>d the pis<strong>to</strong>n <strong>be</strong>ingmade <strong>to</strong> similar limitations. So a new engine pis<strong>to</strong>n could have up <strong>to</strong> 4 thou’ “play” ifassembly was not checked for quality. To limit this, pis<strong>to</strong>ns would <strong>be</strong> graded so theassembler could select a set that would not <strong>be</strong> so slack. Camshafts <strong>an</strong>d cr<strong>an</strong>kshaftswould <strong>be</strong> under similar <strong>to</strong>ler<strong>an</strong>ces, ( ie, a half <strong>to</strong> one thou’ plus or minus,) simply<strong>be</strong>cause machines did not exist that could turn out thous<strong>an</strong>ds of parts without tinydifferences. Experienced assembly line workers, worth their weight in gold, at Morris<strong>Engine</strong>s, could select the correct parts <strong>to</strong> fit <strong>to</strong>gether within the <strong>to</strong>ler<strong>an</strong>ces. Morris paidgood wages <strong>an</strong>d had a large staff of Quality Inspec<strong>to</strong>rs, <strong>an</strong>d used the <strong>be</strong>st materials. Sounlike Rolls Royce, cars for the masses like Morris <strong>an</strong>d M.G. are not perfect, but as closeas possible within a price.Like other m<strong>an</strong>ufacturers, parts that failed the ‘go, no-go’ gauges were thenmachined <strong>to</strong> the next size for ‘exch<strong>an</strong>ge engines’, ie <strong>be</strong>coming <strong>an</strong> undersize cr<strong>an</strong>kshaft,or a rebored block. Nothing was wasted. A ‘go, no-go’ gauge is used <strong>to</strong> check thedimentions of items, giving the limits for <strong>an</strong> opera<strong>to</strong>r <strong>to</strong> use easily <strong>an</strong>d quickly.Comp<strong>an</strong>y PolicyMo<strong>to</strong>r m<strong>an</strong>ufacturers are comp<strong>an</strong>ies, <strong>an</strong>d comp<strong>an</strong>ies exist <strong>to</strong> make money, not cars.Often the m<strong>an</strong>agement are not all enthusiasts, but businessmen <strong>an</strong>d women, <strong>an</strong>d agood idea in business is <strong>to</strong> use common base components. This keeps prices down,allows more choice within a r<strong>an</strong>ge, <strong>an</strong>d c<strong>an</strong> keep quality up, <strong>be</strong>cause of massproduction.In M.G’s case it me<strong>an</strong>t they had access <strong>to</strong> massive investment that was notfor only them, but all the other marques as well. Under BMC this me<strong>an</strong>t they could usenew engines first that on their own they could never have afforded <strong>to</strong> develop <strong>an</strong>dproduce. Under Nuffield it was a similar case. It is no good <strong>be</strong>ing a self contained unitin a comp<strong>an</strong>y if you c<strong>an</strong>not call on its larger resources or help. If the bits you use, likeengines <strong>an</strong>d other mech<strong>an</strong>ics, are suitably modified <strong>to</strong> suit your needs, ie enginestuned for sports cars, but backed by long reliable service in more mund<strong>an</strong>e cars, a carc<strong>an</strong> still have dignity <strong>an</strong>d quality. For inst<strong>an</strong>ce M.G. produced 524,862 MGB’s, but noone noticed that BMC produced 900,000 Farina saloons, both have the ‘B’ series. Or that<strong>be</strong>tween 1953 <strong>an</strong>d 1955 M.G. made 9,600 TF Midgets, but Wolseley made 30,000 4/44saloons, both have late versions of the Morris ‘XP’ series engine. Or that M.G. made150,496 ‘A’ series engined Midgets, but in the Morris Minor there were 1,293,331 alone.9

ProductionThe Beginnings of <strong>an</strong> <strong>Engine</strong>Any engine <strong>be</strong>gins life as <strong>an</strong> idea, ( often tempered by the need <strong>to</strong> re-use parts of theold one due <strong>to</strong> costs,) then a drawing, then this is tr<strong>an</strong>sferred in<strong>to</strong> the three dimensionalwooden ‘pattern’ that will <strong>be</strong> used <strong>to</strong> make the moulds it will <strong>be</strong> cast in. The Morrisdesign office <strong>an</strong>d pattern makers shop was at Cowley, as was the iron foundry. Laterthe Ward End premises of Wolseley would <strong>be</strong> involved in engines as well. The woodenmould will <strong>be</strong> given a num<strong>be</strong>r, often the items part num<strong>be</strong>r, taken from the designoffices drawing num<strong>be</strong>r. This num<strong>be</strong>r will follow the item through <strong>to</strong> the spares booksometimes. For inst<strong>an</strong>ce the XPAG TC/YA cylinder block is pattern num<strong>be</strong>r 24146, theMGB 1798cc five main <strong>be</strong>aring cylinder block is 12H3503, the same as the Marina 1800<strong>an</strong>d the Sherpa 1800 diesel. The 1800 Marina cylinderhead is 12H2709, <strong>an</strong>d the Midget1098cc cylinderhead 12G206. These num<strong>be</strong>rs are cast on<strong>to</strong> the metal <strong>an</strong>d easily seen<strong>an</strong>d rough looking, do not mistake them for serial num<strong>be</strong>rs, ( the engines individualidentity num<strong>be</strong>r,) that are stamped in much later during production. The medium usedfor the engine block <strong>an</strong>d cylinderhead, is often grey cast iron, as this flows very easily<strong>an</strong>d will make intricate castings, <strong>an</strong>d if cooled slowly will form graphite flakes in themetal. Graphite assists easy machining <strong>an</strong>d makes the casting hard wearing, <strong>an</strong>dpartially self-lubricating. Grey cast iron also has a very small shrinkage rate aftercasting, unlike aluminium. Cast iron cylinderheads c<strong>an</strong>not withst<strong>an</strong>d leadfree petrolon the exhaust valve seats, unless they are modified by fitting hardened steel inserts.The Pattern Maker who cut <strong>an</strong>d carved the wooden pattern, will have had <strong>to</strong> make <strong>an</strong>outer pattern, <strong>an</strong>d one that is infact the hollow innards of the engine, such as the waterspaces, called a ‘core’. These are in the ‘negative’ so <strong>to</strong> speak, as the casting is done inspecial sticky s<strong>an</strong>d, hence the term ‘s<strong>an</strong>d-casting’. A negative s<strong>an</strong>d mould is made ofthe engine block, or head, then a ‘core’ mould is made in s<strong>an</strong>d <strong>an</strong>d baked, thensuspended inside the first, via ‘core holes’. Once the iron is poured in under gravity, itsolidifies around the s<strong>an</strong>d shapes. It is then broken open <strong>an</strong>d the cooled castingcarefully cle<strong>an</strong>ed of all s<strong>an</strong>d, both externally <strong>an</strong>d from the ‘core’, the waterways <strong>an</strong>dports, etc. The holes that once supported the core are then machined, <strong>an</strong>d core-plugsfitted, thin discs of concaved steel sprung in<strong>to</strong> place, in the machine shop after. Greycast iron was used almost universally for car engines, until aluminium suppl<strong>an</strong>ted it inmodern cars once costs dropped. A s<strong>an</strong>d casting has a natural ‘s<strong>an</strong>dy’ finish, you c<strong>an</strong>almost make out the grains.After the foundry where the casting takes place, the block <strong>an</strong>d head will <strong>be</strong> fed on<strong>to</strong>tr<strong>an</strong>sfer machines, simply me<strong>an</strong>ing that after each machining it is au<strong>to</strong>maticallytr<strong>an</strong>sferred <strong>to</strong> the next stage of machining, m<strong>an</strong>y times over. This au<strong>to</strong>mation saveslabour, is quicker <strong>an</strong>d more accurate, often just one opera<strong>to</strong>r watching m<strong>an</strong>y machines.In the early days, the rough castings were taken from the Cowley foundry <strong>to</strong> Coventryfor machining. Areas such as the cylinder bore, camshaft <strong>an</strong>d main <strong>be</strong>aring in-lineboring need <strong>to</strong> <strong>be</strong> very accurate. To locate parts accurately with their neighbour,dowels are used, on such parts as flywheels <strong>an</strong>d big end caps. A dowel is a short pieceof round metal bar that fits in<strong>to</strong> a hole in each half of the two bits that need <strong>to</strong> fit<strong>to</strong>gether. Another method is <strong>to</strong> use a key that fits in<strong>to</strong> a slot <strong>be</strong>tween parts, such as acamshaft gear or sprocket, so the ‘timing’ is accurate. A key is used where the two bits‘drive’ one <strong>an</strong>other, <strong>an</strong>d is often square in cross section. Such methods allow accurate,fast assembly, on production lines.10

Pis<strong>to</strong>ns were made of aluminium alloy, just as they are <strong>to</strong>day, but carefully groundoval <strong>an</strong>d tapered <strong>to</strong> cope with the thermal exp<strong>an</strong>sion when in use. Some pis<strong>to</strong>ns hadsteel inserts <strong>to</strong> control their exp<strong>an</strong>sion cast inside them, others are forged from goodquality alloys. To seal up the cylinder bore from oil loss one way <strong>an</strong>d compression lossthe other, pis<strong>to</strong>n rings are used. Connecting rods, camshafts <strong>an</strong>d cr<strong>an</strong>kshafts wereforged from good quality carbon steel. Casting is using melted metal poured in<strong>to</strong> amould; forging is forcing very hot <strong>an</strong>d pli<strong>an</strong>t metal in<strong>to</strong> the required shape, using verypowerful machine hammers, in<strong>to</strong> dies. A ‘die’ is a steel former, usually in two halves<strong>an</strong>d often very large. Because of their accuracy <strong>an</strong>d special steel, they cost a fortune.Forging keeps the ‘grain’ of the metal in the components, giving great strength afterheat treatment. Because the steel parts need <strong>to</strong> <strong>be</strong> hardened <strong>an</strong>d tempered for use in theengine, they are ground in<strong>to</strong> shape, on grinding machines working at very greataccuracy. Areas like the big ends, main <strong>be</strong>arings, camshaft <strong>be</strong>arings <strong>an</strong>d lo<strong>be</strong>s, alsoneed very highly polished finishes, as well as accuracy.Morris <strong>Engine</strong>s Ltd. engines were well made. They used not only cast iron heads<strong>an</strong>d blocks, but often had cast aluminium rib<strong>be</strong>d sumps, clutch <strong>an</strong>d timing chaincovers, with big brass threaded oil fillers <strong>an</strong>d sump plugs. When BMC arrived in 1953such expensive parts were replaced by pressed steel sumps <strong>an</strong>d covers painted enginecolours, often red for M.G. <strong>an</strong>d green for the others. Rover went back <strong>to</strong> rib<strong>be</strong>d alloycovers <strong>an</strong>d sumps, but their whole engines were aluminium alloy castings.It is easy <strong>to</strong> see why the engine, gearbox, <strong>an</strong>d axles are often the major costing in <strong>an</strong>ycar. There are inlet <strong>an</strong>d exhaust m<strong>an</strong>ifolds <strong>to</strong> cast in iron, some inlets in alloy, sumps<strong>an</strong>d timing chain covers cast in aluminium, all <strong>be</strong>arings surfaces need machining <strong>an</strong>d<strong>an</strong> expensive journal <strong>to</strong> rotate in, lined with white metal or other alloy. Inlet <strong>an</strong>dexhaust valves <strong>to</strong> machine <strong>an</strong>d grind, timing gears <strong>an</strong>d oil pumps <strong>to</strong> <strong>be</strong> gear-cut, oilways <strong>to</strong> <strong>be</strong> drilled, <strong>an</strong>d so on. Great care <strong>an</strong>d cle<strong>an</strong>liness is needed during assembly, as<strong>an</strong>y s<strong>an</strong>d or metal swarf ( bits of metal left over after machining,) will quickly ruin <strong>an</strong>engine.Because machining of metal surfaces is again a compromise, <strong>to</strong> ensure there is <strong>an</strong> oiltight seal, or compression tight seal, gaskets are used. This is <strong>an</strong> as<strong>be</strong>s<strong>to</strong>s or paperbased sheet, sometimes with copper surfaces, <strong>an</strong>d is there <strong>to</strong> take up all the tinyimperfections the machine <strong>to</strong>ols left. The sealing of cr<strong>an</strong>kshafts at both ends of theengine, was not a good point of British <strong>Engine</strong>ering in those early days. The front endrelied on a felt ( compressed woollen waste,) seal <strong>an</strong>d the rear a ‘reverse scroll seal’based on the method the Egypti<strong>an</strong>s used <strong>to</strong> lift water from the River Nile 3000 yearsago. As the engine rotates the reverse ‘thread’ is supposed <strong>to</strong> ‘roll’ back in <strong>an</strong>y escapingoil that the ‘oil-thrower’ missed, (<strong>an</strong> oil-thrower is a disc designed <strong>to</strong> spin oil awayfrom the seal area.) The XPAG, ‘A’ <strong>an</strong>d ‘B’ series engines used this system, until BMCfitted neoprene sprung lip-seals in the early 1960’s. Morris were also clever with theirpre-war sv units, putting a ‘cover’ on the <strong>to</strong>p similar <strong>to</strong> a rocker cover, but was infact aair silencer/fume collec<strong>to</strong>r for the carburetters. This has caught out a few ‘experts’ whoassumed they were ohv engines.11

Chapter TwoM.G. <strong>Engine</strong>s from the TA Midget onwardsThe pedigree of the Morris <strong>Engine</strong>s Division included not only the background ofHotchkiss, but that of Wolseley, of Ward End, Coventry, whom Morris had purchasedin 1927. He was after the Wolseley engines of adv<strong>an</strong>ced design, as well as w<strong>an</strong>ting <strong>to</strong>outbid his competi<strong>to</strong>r Her<strong>be</strong>rt Austin. The overhead camshaft engines (ohc) ofWolseley had found their way in<strong>to</strong> m<strong>an</strong>y M.G. cars including the tiny M-type Midget.<strong>How</strong>ever, these ohc engines based on Wolseleys WW1 experience of building Hisp<strong>an</strong>o-Suiza aircraft engines under licence, had proved <strong>to</strong> <strong>be</strong> expensive <strong>to</strong> produce <strong>an</strong>dcomplex <strong>to</strong> keep running. So most Morris cars were fitted with humble side valve (sv)engines, <strong>an</strong>d the Wolseley using a cheap overhead valve (ohv) conversion of the sameengines. For by 1935 Wolseleys had <strong>be</strong>come <strong>an</strong> up-market Morris, though after WW2there was a short return <strong>to</strong> the ohc six cylinders for a while for big Wolseley cars. In1938 Nuffield purchased Riley Mo<strong>to</strong>rs, who had their own well designed four cylinderhigh-camshaft engine, but this engine never affected M.G. as Riley were left <strong>to</strong> runthemselves for some time.The PA/PB ohc Midgets were the last model <strong>to</strong> use that engine, the ohc MorrisMinor reverting <strong>to</strong> a side valve back in 1932, <strong>an</strong>d had <strong>be</strong>en the source of m<strong>an</strong>y of theMidgets components. When the tiny ohc ‘M’-based Midgets engine s<strong>to</strong>ppedproduction, in the upheaval of Leonard Lords thinning out of the numerous modelsM.G. <strong>an</strong>d Morris/Wolseley were building in 1935, M.G. had <strong>to</strong> look in<strong>to</strong> the Morriscupboard of engines for a successor <strong>to</strong> the nice ex-Wolseley units.. From the ratherempty shelves they found the ohv conversion of the pedestri<strong>an</strong> Morris 10/4 Series 2 svunit, ( 10hp four cylinder.) This was fitted <strong>to</strong> the Series 3 Morris 10/4 <strong>an</strong>d Series 2Wolseley Ten/40, ( 10hp rating with 40 brake-horse power, or bhp,) in 1935, <strong>be</strong>ingtermed a ‘MPJW’ in the Wolseley <strong>an</strong>d a ‘MPJM’ in the Morris, <strong>an</strong>d was of 1292cc, witha bore of 63.5mm <strong>an</strong>d a 102mm stroke. This 102mm stroke c<strong>an</strong> <strong>be</strong> traced back <strong>to</strong> theearly Bull Nose Morris engines as well. The rather out of date 1910 RAC rules on HorsePower (hp) still had effect, <strong>an</strong>d was used by the government for levying road tax <strong>to</strong>lls.This rule relied on only the bore of the engine for its formula, in this case giving theseNuffield four cylinder cars a rating of 10hp. After 1936 all the Morris firms werecombined in<strong>to</strong> The Nuffield Org<strong>an</strong>isation, (Morris <strong>be</strong>coming Lord Nuffield in 1935,) <strong>to</strong>get around super-tax problems, as one or two were the personal & private property ofWilliam Morris. There were other parts from the Morris Ten/Four series 3 that were <strong>to</strong><strong>be</strong> used on the ‘M’-type Midgets replacement, the ‘TA’, such as hydraulic brakes,gearbox, axles, etc.Do not confuse “hp” with “bhp”. The old Horse Power (hp) was just that, the powerof one horse. The RAC designed a system whereby cars engines power could <strong>be</strong>worked out by a formula, using the diameter of the bore. This was all right in the early1920’s, but as ‘power measurement’ <strong>be</strong>came more accurate, a machine called a ‘Brake’was used. The engine was bolted <strong>to</strong> it, run up <strong>to</strong> speed, <strong>an</strong>d its output measured inBrake Horse Power, (bhp.) The old RAC system <strong>be</strong>came a joke, a 10hp car wouldproduce over three times that by the 1930’s, for inst<strong>an</strong>ce a 10hp Morris producing37bhp. But the Excise/ Tr<strong>an</strong>sport Ministry, in the ways of British-red tape, kept the old1910 RAC system <strong>to</strong> use for cars <strong>to</strong> pay their road tax on, little cars low <strong>an</strong>nual tax, bigcars more. It was ab<strong>an</strong>doned after WW2, as it had held back engine development byrestricting bore sizes, hence the large num<strong>be</strong>r of old British cars with long strokes <strong>an</strong>dtiny bores!!12

Industrial use of the sidevalve Morris 18hp six. Note the fume-extrac<strong>to</strong>r that looks like a rocker cover. Ab<strong>an</strong>donedin a Welsh slate mine.The related MG WA six cylinder overhead valve engine, showimg tlc.13

VA One <strong>an</strong>d a Half Litre Saloon <strong>Engine</strong> (1937-39)The TA sports car was not the only M.G. <strong>to</strong> inherit a Morris/Wolseley ohv engine,the big M.G. saloon cars used similar ironwork. The VA was <strong>an</strong> M.G. saloon car, thesmallest of a r<strong>an</strong>ge. The VA used <strong>an</strong> engine of 1549cc, with a 69.5mm bore by the nowfamous 102mm stroke version of the Series 2 Wolseley Twelve/48, (infact a big Series2 Ten/40, [TA] engine,) itself a ohv conversion of the Series 2 Morris Twelve/four svunit. The 12hp engines size was why the VA was called the ‘One <strong>an</strong>d a Half Litre M.G.’This was a four cylinder engine <strong>an</strong>d a very close relative <strong>to</strong> that used in the TA Midget,<strong>be</strong>ing of the same Morris family of units. It had a nice rib<strong>be</strong>d aluminium alloy sump.Like the ‘TA’ the car had coil ignition, the distribu<strong>to</strong>r having a vernier adjustment forfine tuning. Cooling relied on thermo-syphon with pump assist<strong>an</strong>ce. Both 10hp <strong>an</strong>d12hp cars used virtually the same gearbox so swapping about was made easy. In the VAthe engine was called a ‘TPBG’. The rather staid unit had a surprise in it, as part waythrough production there were modern steel backed shell <strong>be</strong>arings on the cr<strong>an</strong>kshaft,replacing the direct cast white metal. Morris <strong>Engine</strong>s were updating as they went, asthis engine had two cr<strong>an</strong>kshafts in its short life. There must have <strong>be</strong>en plenty of metalin the VA engine, as it was bored out <strong>to</strong> 73mm <strong>to</strong> give 1705cc, <strong>an</strong>d using Morris 18hp/Wolseley 18/85 pis<strong>to</strong>ns, fitted <strong>to</strong> the TA “Cream Cracker” team cars, ( a ‘TPDG’! ) CecilKim<strong>be</strong>r had such a unit in his own VA it is rumoured, this may <strong>be</strong> true <strong>be</strong>cause thePolice specification VA did use a bored out engine, <strong>to</strong> 1705cc, <strong>to</strong> give it <strong>be</strong>tterperform<strong>an</strong>ce. The VA of 1937 <strong>to</strong> 1939 produced 55bhp at 4,800rpm, on a 6.5 <strong>to</strong> 1compression ratio. Unlike the TA, the VA had <strong>be</strong>en able <strong>to</strong> adopt the dry clutch of the12hp Morris <strong>an</strong>d Wolseley Twelve/48, as they gained it during production. The firstVA engines still had ‘wet’ cork clutches, like the TA. The later VA engines revved moreeasily with the lighter flywheel of the dry clutch.The late 1930’s saw m<strong>an</strong>yimprovements <strong>to</strong> Morris engines.SA Two Litre Saloon <strong>Engine</strong> (1935-38)The SA was the next model up the M.G. saloon car r<strong>an</strong>ge with a six cylinder engine,a more eleg<strong>an</strong>t car th<strong>an</strong> the VA. The SA had the ohv engine from the Wolseley Super Sixof 2062cc, of 16hp, with 75bhp, <strong>an</strong> in-line six cylinder, <strong>an</strong>d the reason the car wasoriginally called the ‘M.G. 2 litre’. In the M.G. it used twin downdraft SU carburetters<strong>an</strong>d had the early Morris ‘wet’ cork clutch. A modern feature was its counterbal<strong>an</strong>cedcr<strong>an</strong>kshaft. It was also used as a sv in the Morris 16hp saloon. Oil pressure was a high80 lbf/in, <strong>an</strong>d was fed <strong>to</strong> the pump from a floating mesh filter in the rib<strong>be</strong>d aluminiumsump, <strong>to</strong> reduce the ch<strong>an</strong>ce of sucking up <strong>an</strong>y sludge in the bot<strong>to</strong>m. Again the coilignition had a vernier adjustment on the distribu<strong>to</strong>r, perhaps a sign of the varying fuelqualities available at the time. As in the ‘VA’, cooling was pump assisted thermosyphon.Tappets held in by circlips are carried in removable ‘tables’ of four <strong>to</strong> each set,( three tables for a six cylinder, ) as they all are on this family of engines. The exhaustwas twin three br<strong>an</strong>ch m<strong>an</strong>ifolds with ‘MG’ cast in, <strong>an</strong>d the sump a rib<strong>be</strong>d alloycasting. To cope with the heavy M.G. SA saloon body, the engine was bored out <strong>to</strong>2288cc using a 69mm bore, ( 17.7hp,) which just happend <strong>to</strong> <strong>be</strong> half a millimetre underthe size of the Morris sv 18hp, <strong>an</strong>d Wolseley 18hp ohv engines. The inlet valves were33mm, <strong>an</strong>d the exhaust valves 30mm diameter. With main <strong>be</strong>arings of 55mm diameter,<strong>an</strong>d big ends of 48mm diameter the connecting rods had pinch-bolt little ends. Pis<strong>to</strong>ndesign ch<strong>an</strong>ged after engine No.QPHG1165, formerly they had four rings, after theyhad just three above the gudgeon pin, in the Aerolite forged items. Oil capacity was 214

The MG VA 1292cc engine, a close relative <strong>to</strong> the Morris Twelve/4, <strong>an</strong>d the Wolseley 12/40. The MG uses twinsemi-downdraft carburetters.Very similar <strong>to</strong> look at,but this 1250cc XPAG MG TD engine is much more modern internally. Its Morrisrelation is the Morris Ten, series ‘M’.15

Down draught SU carburetters ofthe MG SA Two litre saloon,similar <strong>to</strong> those above.The induction <strong>an</strong>d exhaust system. TwinS.U. carburetters of downdraught type taketheir air through a large cle<strong>an</strong>er <strong>an</strong>d silencer.Twin carburet<strong>to</strong>rs are fitted <strong>to</strong> thenew MG TB Midget engine.16

1/2 gallons, with a hot running pressure of 40-60 lbf. The six cylinder Morris engineswere virtually a ‘four’ with two extra cylinders, m<strong>an</strong>y parts were interch<strong>an</strong>geable <strong>to</strong>keep production costs down, not <strong>an</strong> unusual reason for a mass producer ofcomponents such as cars. Later this engine was again enlarged, bored out <strong>to</strong> 2322cc in1938, with a 69.5mm bore, so that aligned it with the ‘QPHW’ Wolseley 18hp, the M.G.version <strong>be</strong>ing the ‘QPHG’, <strong>an</strong>d <strong>to</strong> increase power <strong>to</strong> compete with the new SS Jaguarmodels. The Nuffield system of engine prefixes is explained later. The SA engine of1936 <strong>to</strong> 1939 in 2322cc form with 6.5 <strong>to</strong> 1 compression, produced 80bhp at 4,800rpm,<strong>an</strong>d had that 102mm s<strong>to</strong>ke. It was a bit pointless still calling it the ‘2 litre’ at thatcapacity, <strong>an</strong>d was replaced by the ‘WA’ 2.6 M.G.WA Two Point Six Saloon <strong>Engine</strong> (1938-39)The bigger WA 2561cc in-line six cylinder ohv engine with 73mm bore, again hadthe 102mm stroke of the family of Morris engines, but was <strong>an</strong> improved version with acounter-bal<strong>an</strong>ced cr<strong>an</strong>kshaft, <strong>be</strong>ing built after some engineering improvements <strong>to</strong> theproducts, including thin wall steel backed white metal shell <strong>be</strong>arings located bydowels, <strong>an</strong>d a dry clutch. It replaced the SA. The WA was <strong>an</strong> even gr<strong>an</strong>der M.G. salooncar almost in the small Rolls Royce tradition, <strong>an</strong>d the <strong>to</strong>p of the r<strong>an</strong>ge of these late1930’s saloons. Pis<strong>to</strong>ns were modern controlled exp<strong>an</strong>sion type. It had a two gallonalloy rib<strong>be</strong>d sump, with a six br<strong>an</strong>ch cast exhaust m<strong>an</strong>ifold, covered in cooling ribs.There was a full flow oil filter, <strong>an</strong>d the oil was fed via a coiled copper pipe, from thepump, through the water jacket, <strong>to</strong> the <strong>be</strong>arings. This heated the oil up on starting, <strong>an</strong>dcooled it once <strong>to</strong>o hot. The engine was rub<strong>be</strong>r mounted for insulation, <strong>an</strong>d sported <strong>an</strong>ice aluminium alloy rocker cover. The engine’s cubic capacity was why the WA wascalled the ‘M.G. Two-point-Six’. Again a sv version of the same 2561cc was used in theMorris 18hp, <strong>an</strong>d a similar ohv unit in the Wolseley 18/85. The M.G had twin semidowndraftSU carburetters, <strong>an</strong>d was rated at 19.2hp for road tax.These were all push rod ohv units in the TA, VA, SA, <strong>an</strong>d WA from the Morrisstables, a very unexciting bunch of saloon car side valve engines converted <strong>to</strong>overhead valve operation. All had proper water pumps with a complex thermostat inits own housing with a by-pass, not completely relying on thermo-syphon circulation,coil ignition, <strong>an</strong>d a distribu<strong>to</strong>r with au<strong>to</strong>matic adv<strong>an</strong>ce <strong>an</strong>d retard by centrifugalweights. All used the then ‘new’ smaller diameter 14mm spark plugs, <strong>an</strong>d a timingchain with ‘bright’ “T” links <strong>to</strong> assist in camshaft timing on assembly. M.G. was adivision of Nuffield now, not virtually au<strong>to</strong>nomous <strong>an</strong>ymore, it had <strong>to</strong> followcorporate comp<strong>an</strong>y policy. For the first time M.G. engines had air silencers on in thesaloons, M.G. w<strong>an</strong>ting <strong>to</strong> refine their models, <strong>an</strong>d the saloons had a lot of the bigWolseley saloons in their mech<strong>an</strong>ics. Only the SA <strong>an</strong>d WA had a counter bal<strong>an</strong>cedcr<strong>an</strong>kshaft <strong>an</strong>d all were long stroke, narrow bore units. The WA of 1938 <strong>to</strong> 1939produced 100bhp at 4,800rpm, on a compression ratio of 7.25 <strong>to</strong> 1, both good figuresfor then. For comparison, Hum<strong>be</strong>r had a huge sv 4139cc ‘Blue Ribb<strong>an</strong>d’ engine tha<strong>to</strong>nly produced 113bhp, in their Snipe, during the same years, <strong>an</strong>d it was popular withthe Metropolit<strong>an</strong> Police. The engines in use by M.G. in the late 1930’s were from theparent comp<strong>an</strong>ies s<strong>to</strong>cks. Abingdon had the choice of those power units fitted <strong>to</strong>various side valve Morris saloon cars, from a 918cc 8hp up <strong>to</strong> 3,485cc 25hp, <strong>an</strong>d theiroverhead valve conversions used in the up market Wolseley cars of identical cylinderdimensions, six of which were six cylinder engines, <strong>an</strong>d nearly all with .019" tappetclear<strong>an</strong>ces............. though the ‘ Two Litre’ <strong>an</strong>d ‘TA’ having .015" clear<strong>an</strong>ces. One of these17

engines was <strong>to</strong> lead <strong>to</strong> a very famous line, <strong>an</strong>d that was the ‘MPJG’ four cylinder 1292ccone fitted <strong>to</strong> the ‘TA’, ex- sv Morris Ten/Four conversion.Odd information...the TA, SA, VA <strong>an</strong>d WA dynamo/tacho reduction ratio is 7:15.The carburetters of the One <strong>an</strong>d aHalf Litre, a bigger engine but veryclosely related <strong>to</strong> the TA. Infact theVA & TA engines could <strong>be</strong> swappedover without diffuculty, as long asthe cluthes matched.Twin SU carburetters of the TAMidget. The porting of the MPJGis shown well here, just like thelaster BMC engines.18

THE ‘TA’ Midget “MPJG” <strong>Engine</strong>(MPJW in Wolseley, MPJM in Morris)The ‘TA’ Midget was a much bigger car th<strong>an</strong> the tiny ohc 746/847/939cc, ‘P’ <strong>an</strong>d ‘Q’types it replaced, <strong>an</strong>d thus heavier. It has the Series 2 Wolseley Ten/40 engine, withtwin SU HV3 1 1/8" carburetters fitted <strong>an</strong>d a camshaft with 11:59:56:24 valve timing,8mm lift, producing 45bhp in this M.G.. Considering this was a developed ohv versionof the Series 2 sv Morris Ten/Four this power output was excellent, but it was as far asthis unit could <strong>be</strong> developed or economically go. Whilst more power could <strong>be</strong> wrungfrom it, its long stroke of 102mm, bore of only 63.5mm, <strong>an</strong>d un-counterbal<strong>an</strong>cedcr<strong>an</strong>kshaft, along with its siamesed inlet <strong>an</strong>d exhaust ports, limited its revving r<strong>an</strong>ge.The family of the then current Morris engines used siamesed ports, ( two valves <strong>be</strong>ingfed from one hole,) <strong>an</strong>d on the ‘TA’ whilst No.1 <strong>an</strong>d No.4 exhausts had their own port,there were only two inlet ports each feeding two valves. The centre port was for No.2<strong>an</strong>d No.3 exhaust, ( a design <strong>to</strong> <strong>be</strong> repeated in the BMC ‘A’ <strong>an</strong>d ‘B’ series years later!)The inlet valves were 33mm diameter, with the exhaust at 31mm, both with triple valvesprings. Oil pressure ‘hot’ is 60 psi at 30mph, sump capacity <strong>be</strong>ing 11 pints. It was a‘slow’ engine, with a huge flywheel <strong>an</strong>d a cork lined clutch running in engine oil, realvintage stuff from the Bull Nose era. It did have lots of pulling power, good <strong>to</strong>rque, butnot really a sports car unit. <strong>How</strong>ever, <strong>be</strong>cause it was much bigger th<strong>an</strong> the tiny ohc ‘M’engines, in the TA it gave similar perform<strong>an</strong>ce. A bit ahead perhaps, but it pre-dated theTriumph Spitfire engine that the Spridget inherited after the excellent 1275cc ‘A’ series,the 1493cc Triumph unit, <strong>an</strong>d the seven main <strong>be</strong>aring ‘C’ series in the MGC, havingsimilar faults <strong>to</strong> the ‘MPJG’ engine. Not all M.G. engines were good.<strong>How</strong>ever, a good point of this bread <strong>an</strong>d butter ‘TA’ engine was the full-flow oilfilter, that cle<strong>an</strong>ed all the oil <strong>be</strong>fore it arrived at the <strong>be</strong>arings. It was common for somem<strong>an</strong>ufacturers <strong>to</strong> fit by-pass oil filters, that just <strong>to</strong>ok a dribble of oil off the main feedgallery, filtered it then dropped it in<strong>to</strong> the sump. Such a system could take m<strong>an</strong>y miles<strong>to</strong> filter all the oil, <strong>an</strong>d <strong>be</strong>arings were fed with unfiltered lubric<strong>an</strong>t direct from the oilpump. ( The early BMC Austin engines did just this.) The gear type oil pump fitted <strong>to</strong>these Morris engines were very good, well engineered <strong>an</strong>d built <strong>to</strong> last, unlike the early‘A’ series cheap items. The oil was sucked from the sump <strong>to</strong> the pump via a mesh filterthat ‘floated’ on the oil. The rib<strong>be</strong>d aluminium alloy sump held 12 pints of oil, <strong>an</strong>d had<strong>an</strong> external, pressure full-flow oil filter, running pressure hot <strong>be</strong>ing 60 lbf. From theMPJM/MPJW the TA engine inherited white metal, directly cast on<strong>to</strong> the big end,<strong>be</strong>arings, simple steel backed shells were in the future, on the ‘X’ series of engines <strong>to</strong>come. Big ends were 52mm diameter by 38mm long, with 45mm dia. main <strong>be</strong>arings28mm long. Only two undersizes were available, -.010" <strong>an</strong>d -.020", just like the 1275cc‘A’ series later. Pis<strong>to</strong>n design ch<strong>an</strong>ged after MPJG696, the early plain aluminium typehad four rings, with the stepped-scraper oil ring on the skirt, those fitted MPJG697after having three above the gudgeon pin. The oil control was by a slotted-ring. Waterwas pumped around the cooling system, with a thermostat <strong>to</strong> control temperature,when most run of the mill cars relied on thermo-syphon circulation. Unlike <strong>to</strong>dayscars, the water pump had its own grease nipple. A sign of things <strong>to</strong> come is shown inthe ‘TA’ having <strong>an</strong> air silencer that also consumed the engine fumes via a vent pipe.Ignition was by coil, magne<strong>to</strong>s now <strong>be</strong>ing old fashioned, but still used on m<strong>an</strong>ymo<strong>to</strong>rcycles.M<strong>an</strong>y car comp<strong>an</strong>ies of those days had taken the same economical path <strong>to</strong> updatetheir engines, by converting a current sv unit <strong>to</strong> ohv. SS Jaguar did this with DavidBlacks ‘St<strong>an</strong>dard ‘ six cylinder sv, using it as <strong>an</strong> ohv in their SS90 <strong>an</strong>d SS100, real19

An exploded view of the MG TA Midget version of the Morris 10/4 series 3, <strong>an</strong>d Wolseley 10/40 ohv engine of1292cc. A long stroke with a narrow bore unit common of the inter-war years when the RAC formulae for roadtaxation was used. It was a development of the earlier Morris 10/4 s2 side valve engine. Unusually in the MGinstallation it has triple valve springs per valve.20

‘hairdressers’ cars. Hum<strong>be</strong>r went one <strong>be</strong>tter <strong>an</strong>d used a two litre sv designed in 1929for its Hawk model, for the new owners, the Rootes Brothers. This engine lasted upuntil 1954 in the current Hum<strong>be</strong>r Hawk saloon, then it was updated <strong>to</strong> <strong>an</strong> ohv unit.They put it in<strong>to</strong> new ‘Hawk’ of 1955, <strong>an</strong>d the Sun<strong>be</strong>am ‘Talbot’ sports saloon. It lastedup <strong>to</strong> the last four cylinder Hawk <strong>an</strong>d Commer v<strong>an</strong> in 1967. Thats getting yourmoney’s worth from a design indeed! Morris were just as c<strong>an</strong>ny, the 1549cc sv enginefrom the Morris Twelve/Four, ( used as <strong>an</strong> ohv in the M.G. VA <strong>an</strong>d Wolseley 12/48,)had its 102mm stroke cut down <strong>to</strong> 87mm <strong>to</strong> improve rpm, giving 1476cc, fitted with adry modern clutch, shell <strong>be</strong>arings, <strong>an</strong>d called a ‘VS15M’, <strong>an</strong>d used in the post warCowley up until 1954, <strong>an</strong>d as the ‘VS15C’ in the Morris ‘J’ Type v<strong>an</strong>s until 1956. TheBMC 1200cc ‘B’ series ohv was then fitted <strong>to</strong> replace it, having a similar forward sump<strong>to</strong> the ‘Z’ Magnettes, <strong>to</strong> clear the solid front leaf sprung axle on the J type v<strong>an</strong>.The ‘MPJG’ engine had component designs that would continue right up until thelast 1622cc BMC ‘B’ series engine, such as a pinch bolt on the little end gripping thegudgeon pin. Used in the small early ‘A’ <strong>an</strong>d ‘B’ series as well, this method of locatingthe pis<strong>to</strong>n is not good for continuous high rpm.So the TA engine was ‘state of the art’ for its time, <strong>an</strong>d 3,003 of the models were sold<strong>be</strong>tween July 1936 <strong>an</strong>d August 1939, not bad for a tiny firm like M.G. The larger series2 Wolseley 12hp engine of 1549cc, ( the VA engine,) could <strong>be</strong> fitted <strong>to</strong> a TA, as well asthe four speed gearbox of the Morris 10/4 series 3, Wolseley Ten/40 series 2, Morris12/4 s3, <strong>an</strong>d Wolseley Twelve/48 s2, if the M.G. remote gearch<strong>an</strong>ge was used <strong>an</strong>dclutch adapted. If a dry clutch, late VA unit was used, it was not difficult <strong>to</strong> adapt. Suchwas the interchageability of the Nuffield components. To give the TA <strong>be</strong>tteracceleration, the axle ratio was ch<strong>an</strong>ged from 4.875:1 <strong>to</strong> 4.375:1 at MPJG684.Oil LeaksFor all their faults, these Morris engines had good oil feed <strong>to</strong> most of their workingparts. The ‘X’ series had a particularly good feed <strong>to</strong> its ohv rocker shaft <strong>an</strong>d followers,inherited from the MPJM/MPJG series. The feed came up from the rear end of the mainoil gallery, via a copper pipe, <strong>an</strong>d fed under full pump pressure in<strong>to</strong> the hollow rockershaft. Because MG <strong>an</strong>d Morris were worried over rocker wear, the feed was ample, <strong>an</strong>dit assisted cooling of the <strong>to</strong>p of the valves <strong>an</strong>d their springs, via a tiny hole in the rockeritself, spraying out oil. Even <strong>to</strong>day the two bolts that are for holding on the ‘Y’ airsilencer weep oil if a fibre washer is not used.One weekend I needed my <strong>an</strong>cient car <strong>to</strong> go home on a 24hr pass, from my RAFstation in Oxfordshire. The rocker cover gasket leaked, so I made a new gasket up fromsuitable sheeting in the s<strong>to</strong>res, used on the RR Dart Turbo-Prop engine of the Argosy. Ifit is good enough for RR, its good enough for MG. Home I went <strong>to</strong> see the fi<strong>an</strong>cee, fiftymile away in North Bucks. It was a sunny weekend, so we went for a run all the wayover <strong>to</strong> the Malvern Hills, <strong>an</strong>d back. Oh, such days of traffic free roads in the late 1960’s!It was apple picking time in Worcestershire, so we s<strong>to</strong>pped by a stall in a lay-bye <strong>an</strong>dbrought some. I noticed the back of the car look dirty, <strong>an</strong>d on close examination, foundit was covered in oil.Upon opening the bonnet, I was <strong>to</strong> discover that gasket material suitable for thesynthetic OX38 oil used in Turbo-Prop Jet <strong>Engine</strong>s, was no good for SAE30 Mineral Oilusing MG Pis<strong>to</strong>n <strong>Engine</strong>s. The gasket material had literally melted, <strong>an</strong>d oil was21

The cylinderhead ofthe MG JP unit fitted<strong>to</strong> the TA Midget,with siamesed ports.This cut-away drawing of the cylinderhead gives a good idea of the combustioncham<strong>be</strong>rs <strong>an</strong>d value gear.Note the Triple valve springs.The Morris 10 series `M`1140cc ohv engine, developed in<strong>to</strong> the MG 1250cc XPAGCross <strong>an</strong>d longitudinal sections of Morris Ten engine.22

everywhere. I screwed down the two cover nuts as far as I could, <strong>an</strong>d crept <strong>to</strong> the nextgarage <strong>to</strong> fill up with cheap ‘Commercial Oil’ from <strong>an</strong> oil drum, then drove home.With the technology of the 1930’s in the Morris based engines used by MG till 1955,one had <strong>to</strong> accept they would leak a bit of oil as the sealing was not perfect. That is whatI <strong>to</strong>ld my lady friend, ( now my wife,) <strong>an</strong>d she seemed <strong>to</strong> accept it. I do wonder aboutthose cars that followed me, once they switched on their windscreen wipers when itrained, <strong>an</strong>d everything all smeared up. Would they suspect me?23

M.G. The overhead valves are operated by push rods on the T-type ”Midget” . Note the water pump <strong>an</strong>d thermostat.24

Chapter ThreeThe ‘X’ Series of Morris <strong>Engine</strong>s.As Morris themselves found in 1938, by reducing the stroke the rpm r<strong>an</strong>ge could<strong>be</strong> increased of the 1140cc 10hp MPJM, <strong>an</strong>d by getting rid of the heavy cork clutch <strong>an</strong>dflywheel it could rev faster. Including counterbal<strong>an</strong>ces on the cr<strong>an</strong>kshaft ( big weightsopposite the cr<strong>an</strong>kshaft ‘throw’ for each cylinder,) reduced the vibration <strong>an</strong>d smoothedout the power at the higher rev r<strong>an</strong>ge. This also increased the life <strong>an</strong>d reduced the stresson the cr<strong>an</strong>k itself, which now had up <strong>to</strong> date steel backed white metal, or babbit, bigends <strong>an</strong>d main <strong>be</strong>arings, located by dowels. Then redesigning the cylinderhead <strong>to</strong> havesix ports <strong>an</strong>d <strong>an</strong>gling the valves <strong>to</strong>wards the m<strong>an</strong>ifolds, gave excellent breathing withlots of room for future development. Morris did this in 1938, <strong>an</strong>d called the result the‘X’ series of engines, <strong>an</strong>d produced the new 1140cc 10hp, 63mm bore <strong>an</strong>d 90mm stroke,for their new 10hp ‘M’ series saloon. It proved a lively, <strong>to</strong>ugh little unit. The Morrisversion was the ‘XPJM’, with a 6.6 <strong>to</strong>1 compression ratio, producing 37bhp at 4600rpm.The Series 3 Wolseley Ten version arriving in 1939 with the ‘XPJW’, both with a valvetiming of 5;45;45;5. This very modified, virtually a redesign, of the TA- Morris s3 Ten/4 engine, was a winner. M.G. were very pleased, <strong>an</strong>d developed this 1140cc unit <strong>to</strong> suittheir needs by enlarging it <strong>an</strong>d making internal parts stronger. This was <strong>to</strong> <strong>be</strong> the‘XPAG’ once bored out <strong>to</strong> 1250cc, with the now new shorter 90mm stroke <strong>an</strong>d a 66.5mmbore, 7.2/7.4 <strong>to</strong> 1 compression, with its own camshaft with timings of 11;57;52;24, <strong>an</strong>dbigger valves, producing 54bhp at 5200rpm. Morris <strong>Engine</strong>s termed this unit the‘short-stroke Morris Ten ‘M’ engine’. The 1140cc XPJM was designed by one ClaudeBaily, who was later involved in the Jaguar XK series. Because of the bigger pis<strong>to</strong>ns ofthe 1250cc version of the ‘X’ series of engines, <strong>an</strong>d its good rev-ability, the connectingrods were stronger on the M.G. cars th<strong>an</strong> on the 1140cc unit. The ‘TA’ chassis was fittedwith this lively engine, with <strong>an</strong> improved version of the 10hp Morris series ‘M’gearbox, with synchromesh on the upper ratios, <strong>an</strong>d renamed the ‘TB’. The TA enginemounting system was used, the new XPJM front mounting <strong>be</strong>ing adapted <strong>to</strong> suit. Notethat such things as synchromesh was introduced <strong>to</strong> give quiet gear ch<strong>an</strong>ges, notnecessarily faster selection, something worth remem<strong>be</strong>ring if you are use <strong>to</strong> modernfwd cars, <strong>an</strong>d then try driving <strong>an</strong> old M.G.Do not under estimate the TA, it was the first of the world famous ‘T’ series of sportscars that <strong>to</strong>ok the world by s<strong>to</strong>rm after WW2. It will <strong>be</strong> remem<strong>be</strong>red by m<strong>an</strong>y whomthemselves were not even thought of during its time, as that car chosen by m<strong>an</strong>y RAFpilots, <strong>an</strong>d USAF personnel, for the thrill of driving. The engine that powered it was asimple conversion of a saloon car engine that could trace its <strong>an</strong>cestry back <strong>to</strong> the 11.9hpBull Nose Morris, <strong>an</strong>d in 13.9hp size <strong>to</strong> the M.G. 14/28 <strong>an</strong>d 14/40, all with that 102mmstroke.WW2 cut short the life of the TB Midget, the only modification the 1250cc enginegained was <strong>an</strong> oil pressure-powered timing chain tensioner after engine num<strong>be</strong>r 883.Some were fitted with a nice polished alloy rocker cover, from engine num<strong>be</strong>r 2020 <strong>to</strong>2966, which exp<strong>an</strong>ds in<strong>to</strong> the post war TC Midget as only 377 TB’s were made.Theengine fitted <strong>to</strong> the ‘TB’ was now very up <strong>to</strong> date <strong>an</strong>d was <strong>to</strong> survive until 1956. Theredesign had resulted in its power rising from 45bhp <strong>to</strong> 54bhp at 5200rpm, in a muchlivelier package with <strong>an</strong> unburstable feeling <strong>to</strong> it, a sports car engine.25

Side view of the 1250cc carburetter XPAG/SC MG engine as fitted <strong>to</strong> the ‘Y’ series saloon in 1947, with theearly smooth 9 pint sump.26

The ‘X’ series of engine has the sump face one eighth of <strong>an</strong> inch <strong>be</strong>low the centre lineof the cr<strong>an</strong>kshaft, easily noticed on the front timing cover/sump as<strong>be</strong>s<strong>to</strong>s string seal,the two ‘halves’ are infact different lengths. Like most four cylinder, three main <strong>be</strong>aringengines, the side thrust is taken on the centre main <strong>be</strong>aring fl<strong>an</strong>ges. The fact the block isbolted <strong>to</strong> the cast aluminium sump, <strong>an</strong>d both bolt <strong>to</strong> the clutch <strong>be</strong>ll housing, makes theengine <strong>an</strong>d gearbox unit very rigid. The, initially, split skirt later solid skirt, Aerolitealuminium pis<strong>to</strong>ns, have two cast iron compression rings, <strong>an</strong>d one slotted oil scraperring. On the M.G. XPAG the valves had double springs. The cylinderhead carried themajor water flow for cooling, <strong>be</strong>ing fed in<strong>to</strong> the rear of the head, via a waterway alongthe offside under the m<strong>an</strong>ifolds. A water pump then assisted the hot water <strong>to</strong> theradia<strong>to</strong>r from the front of the head. The cylinder block relied on internal thermosyphonfor its cooling. The engine had a very complex thermostat in its own housing.Variations in the ‘X’ Series of <strong>Engine</strong>sM.G. really <strong>to</strong>ok the little XPAG <strong>to</strong> heart, <strong>an</strong>d it found its way in<strong>to</strong> m<strong>an</strong>y M.G.models, as well as some Morris <strong>an</strong>d Wolseley’s. Study the chart <strong>to</strong> follow its use.Model bore/stroke type cc madeMorris 10/4 s2 63.5 by 102 sv 1292 1935-37Morris 10/4 s3 63.5 by 102 ohv MPJM 1292 1937-38Wolseley 10/40 s2 63.5 by 102 ohv MPJW 1292 1937-38M.G. TA Midget 63.5 by 102 ohv MPJG 1292 1936-39Morris 10/4 s ‘M’ 63.5 by 90 ohv XPJM 1140 1938-48Morris 10/4 Utility .. .. XPJM/U 1140 1939-45Wolseley Ten s3 .. .. XPJW 1140 1939-48M.G. TB Midget 66.5 by 90 ohv XPAG 1250 1939M.G. TC Midget .. .. XPAG .. 1945-49M.G. TD Midget .. .. XPAG/TD .. 1949-52M.G. TD mk2 .. .. XPAG/TDC .. 1949-52M.G. TD 8" clutch .. .. XPAG/TD2 .. 1952-53M.G. TD Mk2 8" clutch .. .. XPAG/TD3 .. 1952-53M.G. YA .. .. XPAG/SC .. 1947-52M.G. YA 8" clutch .. .. XPAG/SC2 .. 1952M.G. YB .. .. XPAG/SC2 .. 1952-53M.G. YT lhd .. .. XPAG/TL .. 1948-50M.G. YT rhd .. .. XPAG/TR .. 1948-50M.G. TF Midget .. .. XPAG/TF .. 1953-55Wolseley 4/44 .. .. XPAW .. 1953-56M.G. TF 1500 72 by 90 XPEG 1466 1953-55The TC was the first with a timing chain tensioner, the earlier engines had a 7 1 / 4"clutch, <strong>an</strong>d the Wolseley 4/44 (ch<strong>an</strong>ge of system now, four cylinder with 44 bhp,)engine is really <strong>an</strong> SC/2 with a different sump casting. The ‘type’ will appear on theround brass disc in the centre of the engine num<strong>be</strong>r plate.27

End view of the XPAG/SC 1250cc single carburetter Y saloon engine of 1947.28

Production num<strong>be</strong>rs of the ‘X’ series of engines:Morris ’M’ 80,000 plus,Wolseley 10/40 12,000 estimate,M.G. TA Midget 3,003M.G. TB 379M.G. TC 10,000M.G. TD 28,643M.G. TD Mk2 1,022M.G. TF 6,200M.G. TF 1500 3,400M.G. YA 6,158M.G. YB 1,301M.G. YT 877Wolseley 4/44 30,000 Total 182,604This Figure does not include the m<strong>an</strong>y thous<strong>an</strong>ds of the Morris 10/4 Utility cars &v<strong>an</strong>s made during WW2 with the 1140cc XPJM/U, Solex caburetter engine, or thosefitted <strong>to</strong> petrol/electric sets <strong>an</strong>d pumps as the 1140cc XPJM/U for the war effort. These1140cc engines c<strong>an</strong> <strong>be</strong> bored out <strong>to</strong> 1250cc, but there is no Octagon cast in<strong>to</strong> the block,see Archaeology section on how <strong>to</strong> identify one.The models that used the 1250cc XPAG engine c<strong>an</strong> <strong>be</strong> seen in the list. For normalproduction use variations were kept low, <strong>an</strong>d the modifications made during its lifewith M.G. c<strong>an</strong> <strong>be</strong> seen under that heading. It is very comprehensive, <strong>be</strong>cause it is apopular engine. Should you w<strong>an</strong>t <strong>to</strong> know this much about the BMC ‘B’ series, I wouldguide you <strong>to</strong> the excellent book by Lindsay Porter, see Bibliography. In the ‘T’ types theengine has twin SU H1 1 1/4" carburetters ( TA 1 1/8") with no hot-spot, as the inlet <strong>an</strong>dexhaust m<strong>an</strong>ifolds are separate castings. On the saloon car, the ‘Y’s, there is a single SUH2 1 1/4" carburetter with a huge air silencer above, with a single piece inlet <strong>an</strong>dexhaust m<strong>an</strong>ifold giving a hot-spot <strong>to</strong> assist vapourisation of the mixture. Such asystem is not good for efficiency, as it heats up the incoming charge, but does give <strong>an</strong>ice smooth tick-over <strong>an</strong>d quick engine warm up. The Internal Combustion <strong>Engine</strong>(ice) is a heat engine, <strong>an</strong>d relies on getting air as hot as possible for maximumexp<strong>an</strong>sion. Cold air in with maximum heat produces more power. If you pre-heat theair, you lose out on efficiency. Good cool mixture is <strong>be</strong>st, <strong>an</strong>d this may help <strong>to</strong>wards the54bhp the ‘T’ types produce over the lesser 46bhp of the ‘SC’ engines. Otherwise, as themodifications list shows, they are very similar units. The Wolseley 4/44 has the SC2engine, in this specification, but with a m<strong>an</strong>ifold that faces out over the starter mo<strong>to</strong>r<strong>an</strong>d <strong>an</strong> export oil-bath air filter, where as the M.G’s exhaust m<strong>an</strong>ifold faces downcentrally. The 4/44 cast aluminium sump is completely different, with its reservoir atthe front, rather prone <strong>to</strong> hitting kerbs, a fault of the ‘B’ series in the sister car, the ‘Z’Magnettes, ( see ‘B’ Series.) The introduction of the ‘Y’ type also me<strong>an</strong>t modifications <strong>to</strong>the sump of the TC engine it used. It remained the same 5 ltr ( 9 pints) shape, but hadbosses cast in<strong>to</strong> both sides <strong>to</strong> cope with the LHD <strong>an</strong>d RHD clutch relay levers. Laterboth TD <strong>an</strong>d Y types had bigger 6ltr (10 1/2 pint) sumps, with cooling ribs. Otherobvious modifications were the fitting of a bigger clutch, 7 1/4" growing <strong>to</strong> <strong>an</strong> 8". Thisalso affected the flywheel <strong>an</strong>d the gearbox first motion shaft <strong>an</strong>d <strong>be</strong>ll-housing makinginterchageability difficult. For inst<strong>an</strong>ce I run a replacement ‘SC’ Gold Seal engine withthe old type filter c<strong>an</strong>ister, in <strong>an</strong> early ‘YB’ that has the correct later SC2 gearbox withthe larger first motion shaft <strong>an</strong>d <strong>be</strong>ll housing. This me<strong>an</strong>s the engine will only take a 71/4" clutch plate, but it needs a 3/4" centre. The M.G. 7 1/4" clutch plate has a 5/8"29

Later rib<strong>be</strong>d 10 pint sump, with improved oil pick up <strong>an</strong>d later oil filter, twin carburtter XPAG/TD 1250ccengine used in the TD Midget after 1952.30

centre, but one from a 1950 Hillm<strong>an</strong> Minx fits I am pleased <strong>to</strong> say, as it uses a similar 71/4" clutch plate but with a 3/4" centre. You just have <strong>to</strong> <strong>be</strong> prepared <strong>to</strong> search aboutau<strong>to</strong>jumbles. Whilst the gearboxes all look similar, the sportscars version have theremote gearch<strong>an</strong>ge coming off the ‘<strong>to</strong>p cover’ of the ‘M’ Morris unit, where as the ‘Y’has its remote gearch<strong>an</strong>ge coming off a rear extension tail shaft.Note that SU carburetters, ( Skinners Union,) use ‘H’ for horizontal, ( or semidowndraft)carbs, with num<strong>be</strong>rs after, ie H2. The num<strong>be</strong>r refers <strong>to</strong> the num<strong>be</strong>rs of‘eighths of <strong>an</strong> inch’, ie H2 is a 1 1/14", H4 is 1 1/2" etc.For those interested, it is quite easy <strong>to</strong> fit hardend steel inserts <strong>to</strong> the exhaust valveseats of the XPAG/XPEG/XPAW <strong>to</strong> enable the engine <strong>to</strong> use leadfree petrol. Mostconversions use the bigger valves of the TF <strong>an</strong>d with a bit of cle<strong>an</strong>ing up of the ports,thus you gain a few BHP. XPAG/XPAW inlet valve head diameters are 33mm, exhaust31mm; XPEG inlet 36mm, exhaust 34mm. It is <strong>be</strong>st if the exhaust valve guides arereplaced with phosphor-bronze ones, the normal cast iron versions not liking the lackof lubricating lead, <strong>an</strong>d the valves <strong>be</strong>ing of good quality heat resist<strong>an</strong>t steel, if you c<strong>an</strong>afford it a Nimonic Alloy.Nuffield System of <strong>Engine</strong> Identification & Num<strong>be</strong>ring.The Nuffield (Morris <strong>Engine</strong>s) system of engine identification lasted well in<strong>to</strong> thepost BMC merger, so some early ‘A’ <strong>an</strong>d ‘B’ series engines used it, ( in Morris, Wolseley& MG models,) slightly modified. Prior <strong>to</strong> 1936 a two letter code has <strong>be</strong>en used, thefour letter one follows:-First letter-Model Second-Valves Third-Bore & HP Fourth-MakeU, Morris Eight S, sidevalve H, 57mm 8hp M, MorrisM, Morris 10/4 P, Pushrod ohv J, 63.5mm 10hp G, M.G.X, Morris ‘M’ 10hp C, overhead cam A, 66.5mm 11hp W, WolseleyT, Morris 12/4 B, 69.5mm 12hp C, CommercialQ, 2ltr 6 cylinder E, 72mm 13hpO, 3 1/2ltr 6 cylinder D, 73mm 13hpA, ‘A’ series (A30) D, 61.5mm 14hpV, Postwar Morris/Wolseley, H, 69.5mm 18hp (6 cylinder.)B, ‘B’ series, ( Z Magnette, etc) E, 82mm 25hp, ( 6 cylinder.)12, 1200cc ; 15, 1489cc,22, 2200cc ; 26, 2693ccFor inst<strong>an</strong>ce reading ‘XPAG’ equates <strong>to</strong>” Morris 10/4 engine, OHV, 66.5mm bore11hp, used in M.G.” <strong>an</strong>d ‘BP15GA’ was ” ‘B’ series, pushrod ohv, 1489cc, M.G. ZA”.Some were never used by M.G. such a ‘O’ <strong>an</strong>d ‘V’. The ‘V’, ‘A’, <strong>an</strong>d the ‘B’ were usedafter the war, <strong>an</strong>d dropped the ‘HP’ part, as the RAC rating was out dated by then,replacing it with the cubic capacity, such as the side valve Morris Cowley VS15M, the15 <strong>be</strong>ing 1500cc,( actually 1476cc.) The system is not bomb proof as ‘E’ equates <strong>to</strong> 72mmbore for 13hp as a four cylinder, but jumps <strong>to</strong> a 82mm bore for a six cylinder 25hpengine! The ‘X’ engines were called short-stroke Morris ‘M’ series,( <strong>Engine</strong> 102mmstroke M series; not the car, the Morris Ten Series ‘M’.) In the engine prefix BP15GA, theend ‘A’ refers <strong>to</strong> the model, in this case a M.G. ZA Magnette, BP15GB <strong>to</strong> the ZB, <strong>an</strong>dsoon.31

Where do you find the all import<strong>an</strong>t engine num<strong>be</strong>r? On early XPAG units it is on<strong>an</strong> octagon brass plate riveted <strong>to</strong> the <strong>be</strong>ll housing, just aft of the oil pipe <strong>to</strong> the valvegear. On early 4/44 engines it is in the same place, but this time it is a square brass plate.On the TD, TF, Y <strong>an</strong>d later 4/44’s it is on a similar plate riveted <strong>to</strong> the offside (driversside,) of the cylinder block, under the front core plug under the m<strong>an</strong>ifolds. It is on araised portion of the casting, <strong>an</strong>d some engines have their num<strong>be</strong>r repeated, stampedin<strong>to</strong> the actual casting just above this plate. Reconditioned engines have <strong>an</strong> extrasquare plate just aft of this identity plate, see Archaeology.Power, RPM & ModelsYear Model Cylinders BHP RPM Bore/Stroke comp.1936/39 TA Midget 4 45 4800 63.5 102 6.5:11936/39 SA 2 ltr 6 80 4800 69.5 102 6.5:11937/39 VA 1 1/2 ltr 4 55 4800 69.5 102 6.5:11938/39 WA 2.6 ltr 6 100 4800 73 102 7.25:11938/48 Morris 10 s’M’ 4 37 4600 63.5 90 6.6:11939 TB Midget 4 54 5200 66.5 90 7.25:11945/50 TC Midget 4 54 5200 66.5 90 7.2/7.4:11947/52 YA 1 1/4 ltr 4 46 4800 66.5 90 7.2/7.4:11950/53 TD Midget 4 54 5200 66.5 90 7.2/7.4:11950/53 TD Mk2 Midget 4 60 5500 66.5 90 9.2:11952/53 YB 1 1/4 ltr 4 46 4800 66.5 90 7.2/7.4:11953/55 TF Midget 4 58 5500 66.5 90 8.1:11954/55 TF 1500 Midget 4 63 5000 72 90 8.3:11953/56 Wolseley 4/44 4 46 4800 66.5 90 7.25:1Just by looking at the bore/stroke the families of engines c<strong>an</strong> easily <strong>be</strong> seen. 63bhpfrom 1466cc for 1954 was <strong>an</strong> excellent power <strong>to</strong> engine size ratio. The BMC ‘B’ only pu<strong>to</strong>ut 60 bhp from 1489cc in the first Z Magnette in 1953, ( later improved <strong>to</strong> 68bhp.)Odd information....The XPAG engines dynamo/tacho reduction ratio gearbox is6:15, that of the TA, SA, VA, <strong>an</strong>d WA is 7:15.XPAG Modifications During ProductionTB, TC, TD, TF, & ‘Y’ typesplus Wolseley!Before you read through this list, I emphasise that these mods were duringproduction of the engine, <strong>an</strong>ything could have <strong>be</strong>en done since <strong>to</strong> the unit. Also, itemslike cylinder heads do not carry unique identity num<strong>be</strong>rs, <strong>an</strong>d are often swappedabout.1) First XPAG fitted in<strong>to</strong> the TB Midget, August 1939. WW2 interveined, <strong>an</strong>d modelupdated in 1945 <strong>an</strong>d called the TC. Using two 1 1/4" SU carbs.32

2) Up <strong>to</strong> XPAG 883 (TC) there was no timing chain tensioner. One was fitted from884, <strong>an</strong>d the aluminium alloy cover has a bulge in it <strong>to</strong> accommodate this oil pressurefed, hydraulically damper, spring loaded tensioner. The oil is fed from No1 main<strong>be</strong>aring feed.3) From 2020 <strong>to</strong> 2966 a nice alloy rocker cover was fitted as st<strong>an</strong>dard. It must haveproved expensive, as it was soon deleted <strong>an</strong>d the pressed steel one reinstated.4) In 1947 M.G. introduced the ‘Y’ series saloon, with a single SU H2 1 1/4"carbXPAG engine. This <strong>an</strong>d the softer cam produced 46bhp. There had <strong>be</strong>en no suffix <strong>to</strong> theXPAG engine types up until now as there was only the TC using it. In the ‘Y’ the engine<strong>be</strong>came the XPAG/SC, <strong>an</strong>d <strong>be</strong>g<strong>an</strong> at SC/10001. It was both a saloon now termed theYA, <strong>an</strong>d a <strong>to</strong>urer called the YT, <strong>an</strong>d sold in RHD <strong>an</strong>d LHD. To clear the LHD steeringcolumn the dip stick <strong>an</strong>d its guide grew by two <strong>an</strong>d a half inches at SC/13404. Where asthe TB & TC had a rib<strong>be</strong>d alloy sump, the ‘Y’ type was smooth.5) In 1949 the TC was replaced by the TD, based on the excellent but modified YAchassis <strong>an</strong>d running gear. The first TD engine was XPAG/TD/501. With the new modela new C45Y dynamo, M418G starter <strong>an</strong>d flywheel starter gear ring were fitted, at TD/501 <strong>an</strong>d SC/14023. The new starter only has two bolts, not three. TD engine num<strong>be</strong>rsvery quickly catch up the YA, then overtake it. TD used the Y sump.6) At SC/14083 the oil pump <strong>to</strong> filter pipe ch<strong>an</strong>ged from a two bolt fixing <strong>to</strong> a b<strong>an</strong>jobolt.This required the end cover of the pump ch<strong>an</strong>ging, <strong>an</strong>d a new pipe. It was done <strong>to</strong>clear the steering column of the LHD cars. The XPAG/TL <strong>an</strong>d TR engines were in thenormal num<strong>be</strong>ring system of the SC units, not separate.( SC me<strong>an</strong>s single carb.)7) At SC/15405 <strong>an</strong>d TD/2985 the oil filter type ch<strong>an</strong>ged, <strong>an</strong>d its support strapsmade stronger. The strap fixing bolts <strong>to</strong> the block were increased from two <strong>to</strong> three, <strong>an</strong>dthe straps made wider, one inch <strong>to</strong> one & half inches. Anti-crush ends were fitted <strong>to</strong>s<strong>to</strong>p overtightening <strong>an</strong>d crushing the filter c<strong>an</strong>ister. The pattern for this castingch<strong>an</strong>ged <strong>to</strong> accommodate the three bolts, <strong>an</strong>d hence the casting num<strong>be</strong>r ch<strong>an</strong>ged <strong>to</strong>24445. At this time the engine num<strong>be</strong>r plate moved from the <strong>be</strong>ll housing <strong>to</strong> the offsidefront of the cylinder block, on<strong>to</strong> a ready cast in raised portion. See Archaeology.8) At SC/15576 the pis<strong>to</strong>ns in the YA were commonised with the solid-skirt type ofthe TD. It is very doubtful if m<strong>an</strong>y Y’s still have their original split-skirt pis<strong>to</strong>ns prior <strong>to</strong>this modification in about mid-1950. Solid-skirt pis<strong>to</strong>ns are stronger, but not as quiet.9) At SC/16463 <strong>an</strong>d TD/6482 the water pump gl<strong>an</strong>d seal was improved. Old <strong>an</strong>dnew pumps look identical. At SC/16769 dynamo ch<strong>an</strong>ged <strong>to</strong> a C39PV type.10) The oil pump pick up was <strong>to</strong> the left-h<strong>an</strong>d side of the sump, <strong>an</strong>d it appears tha<strong>to</strong>n fast cornering it could cause oil starvation, ( in a ‘Y’? Must have <strong>be</strong>en on racingTD’s.) The pick up was moved <strong>to</strong> the centre of the sump at SC/16729 <strong>an</strong>d TD/7576.11) On the Y only, at SC/16831, ( see 12 <strong>be</strong>low as well,) the camshaft timing wasaltered <strong>to</strong> that of the Morris Ten series ‘M’ / Wolseley Ten s3 XPJM/XPJW engines,5;45;45;5 but with the 8mm lift of the TD. It had <strong>be</strong>en 6.6mm lift with the TD timing of11;57;52;24. The TD always had 8mm lift. Tappet clear<strong>an</strong>ce remained at the clattery0.019". This was supposed <strong>to</strong> improve mid-r<strong>an</strong>ge <strong>to</strong>rque for the saloon.33

12) But on both the YA <strong>an</strong>d TD the rocker gear was modified. At SC/16831 <strong>an</strong>d TD/9008 the exhaust rockers had their bushes made longer <strong>to</strong> increase life, ( Nos 1,4,5, & 8.)Washers were added <strong>be</strong>tween them <strong>an</strong>d the spacing springs, <strong>an</strong>d the rocker shaft madelonger <strong>to</strong> suit, the old one was 356mm <strong>an</strong>d the new one 376mm. Inlet rockers remainedunch<strong>an</strong>ged.13) Modification <strong>to</strong> the drive chain me<strong>an</strong>t that the engines suffixes were <strong>to</strong> ch<strong>an</strong>ge<strong>to</strong> SC2 <strong>an</strong>d TD2.( Note a TD mk2* has a TD3 engine!) The clutch was enlarged <strong>to</strong> a 8"unit, replacing the 7 1/4", along with the first motion shaft in the gearbox growing <strong>to</strong>3/4" from 5/8". The clutch face on the flywheel was enlarged <strong>to</strong> cope, as was the clutchcover. This moved the starter ring out a little, but it was so machined that its outerdiameter did not ch<strong>an</strong>ge. The gearbox release <strong>be</strong>aring shaft was thicker <strong>an</strong>d slightlyhigher up the slightly wider <strong>be</strong>ll housing. This all occurred at SC2/16916 <strong>an</strong>d TD2/9408, simply continuing the normal num<strong>be</strong>rs sequence. This was prior <strong>to</strong> the YB so SC2engines c<strong>an</strong> <strong>be</strong> found in late YA’s.* TD Mk2 was a special version Midget with a little more power, a bit like <strong>to</strong>day’slimited editions! It uses two 1 1/2" SU carbs, as does the later TF.14) The old disposable,separate oil filter <strong>an</strong>d its associated pipework were deleted,<strong>an</strong>d a modern for 1952 disposable element type fitted. This used the same element thata huge num<strong>be</strong>r of British cars were <strong>to</strong> use in the 1950’s, <strong>to</strong> the 1980’s. This entailed <strong>an</strong>ew oil pump casting, that has the filter bowl integral with it, held on by a long bolt.The oil pipe holes in the cylinder block were left undrilled. The old oil by-pass hole inthe block <strong>be</strong>came the oil feed from the pump in<strong>to</strong> the main oil gallery. A by-pass wasincorporated in<strong>to</strong> the filter housing itself <strong>to</strong> relieve excess high pressure with cold oil. Ifthe oil filter itself <strong>be</strong>came blocked due <strong>to</strong> lack of servicing, it could <strong>be</strong> lifted off itsseating <strong>an</strong>d pass dirty oil, a large spring inside the bowl allowing this. The filter strapswere deleted, <strong>an</strong>d holes left undrilled on the block face. This later oil pump CAN <strong>be</strong>fitted <strong>to</strong> earlier engines if the by pass valve is removed, <strong>an</strong>d the old oil filter feed <strong>to</strong> therear of the gallery is plugged up, ( by the rocker gear oil pipe.) It is a much neaterarr<strong>an</strong>gement, no pipes <strong>to</strong> leak. SC2/17293 <strong>an</strong>d TD2/14224 onwards were so modified.15) The unrib<strong>be</strong>d 9 pint ( 5 ltr,) aluminium alloy TC sump was recast as a 10 1/2 pint( 6 ltr,) sump with cooling fins for the new YB due out in 1952, at SC2/17383. It was alsofitted <strong>to</strong> the TD <strong>to</strong> commonise the engines, at TD2/14948. The oil suction mesh filterpipe was improved, but see SC2/18097, TD2/24489.16) At SC2/17432 <strong>an</strong>d TD2/17298 the pushrods were shortened <strong>to</strong> accommodatelonger rocker adjusting set screws. The threads were longer, <strong>an</strong>d both rods <strong>an</strong>dadjusters were only supposed <strong>to</strong> go with each other, not <strong>be</strong> mixed with earlier parts.17) For the more powerful Midget TD Mk2 the engine had its waterways improved<strong>to</strong> help cooling.Whilst the TD Mk2 had both the new head <strong>an</strong>d block, the normal TD<strong>an</strong>d YB had <strong>to</strong> use up existing s<strong>to</strong>cks. The new items are termed ‘round-hole’ blocks orheads, <strong>an</strong>d carry casting num<strong>be</strong>rs for the head of 168422 head <strong>an</strong>d 168421 block. Thereis no octagon cast in<strong>to</strong> these blocks, as they were also used on the Wolseley 4/44, <strong>an</strong>dhave <strong>an</strong> extra boss for the 4/44 dipstick. This was undrilled on the M.G. ‘oval hole’heads are casting num<strong>be</strong>r 22952, <strong>an</strong>d M.G. XPAG oval hole blocks are 24146 <strong>an</strong>d 24445with octagons. (See casting num<strong>be</strong>r identity for more.) The round hole cylinder blockswere now <strong>be</strong>ing fed on<strong>to</strong> the production line, the oval hole ones all used up. Alas therewere still lots of oval hole heads left. At SC2/17463 <strong>an</strong>d TD2/17969 the round hole34

lock was fitted <strong>to</strong> the YB <strong>an</strong>d TD, note how the TD num<strong>be</strong>rs are now ahead of the YB,the TD was selling rather well. With <strong>an</strong> oval hole head <strong>an</strong>d a round hole block, or visaversa,<strong>an</strong> oval hole head gasket must <strong>be</strong> used, part num<strong>be</strong>r X24481. Round hole headgasket is part num<strong>be</strong>r 168423. See alse item 21 <strong>be</strong>low.18) The specification for the steel used in the exhaust valves was improved, verydoubtful if <strong>an</strong>y old type now remain in use. SC2/17500 <strong>an</strong>d TD2/18291 gained them.Note that like the YT engines in the SC-sequence, the TD Mk2 engines also carriedon inside the normal TD sequence, no separate num<strong>be</strong>ring.19) The distribu<strong>to</strong>r clamp ch<strong>an</strong>ged <strong>to</strong> a cotter bolt, from a simple clamp, at SC2/17670 <strong>an</strong>d TD2/20942. Careful about that distribu<strong>to</strong>r at <strong>an</strong> au<strong>to</strong>jumble, will it fit yourcar?20) Once the sump was drained, there had <strong>be</strong>en problems with priming the oilpump. So at SC2/17670 <strong>an</strong>d TD2/20972 the oil pump gained a priming plug. Youcould fill up the oil pump, <strong>an</strong>d get oil pressure <strong>an</strong>d not heart attack!21) At last the s<strong>to</strong>cks of ready <strong>to</strong> fit oval hole cylinderheads had run out. The otherM.G’s could now have a cooling system like the TD Mk2, with a block <strong>an</strong>d head thatmatched. The heads were fed in<strong>to</strong> the production line, ( casting num<strong>be</strong>r 168422). Thishas long reach plug holes (3/4"), so if you have long reach plugs, it is a round holehead. If you have short reach plugs, ( 1/2"), you have <strong>an</strong> oval hole head. Again if around hole head is fitted <strong>to</strong> a round hole block, use the correct gasket, 168423. Oldheads use Champion L10S plugs, the new one Champion N8B. This happened at SC2/17994 <strong>an</strong>d TD2/22753. At TD2/22251 the clutch cable <strong>be</strong>came a rod.22) To improve the mid-r<strong>an</strong>ge <strong>to</strong>rque of the TD, it gained the YB camshaft, part NoAAA3096, at TD2/24116. <strong>How</strong>ever, it was not quite the same identical camshaft, seeitem 23 <strong>be</strong>low. ( Old TD camshaft was AAA5776.)23) Whilst the ‘new’ cam had the same 5;45;45;5 timings of the YB, it was in fact amore modern profile with wider lo<strong>be</strong>s <strong>to</strong> improve life. The shape of the lo<strong>be</strong> profileenabled the tappet clear<strong>an</strong>ce <strong>to</strong> <strong>be</strong> reduced <strong>to</strong> 0.012" from 0.019", hence it was a lotquieter. It is called the 230 degree cam, with 8.3mm lift. The plate on the rocker covergave the new clear<strong>an</strong>ce, <strong>an</strong>d this was SC2/18097 <strong>an</strong>d the TD2/24116 above. Today wehave the problem of identifying which cam is fitted, see XPAG Camshaft. The XPAG isone of the more audible engines one hears, it lets you know its tappet clear<strong>an</strong>ces are awide .019", <strong>an</strong>d even the later .012" is not so quiet.24) At SC2/18097 the YB gained a new distribu<strong>to</strong>r, 40058F type, <strong>an</strong>d the TD gaininga similar version at TD2/24489, type 40367. These had high lift-short duration cams,<strong>an</strong>d the points gap was 0.014" <strong>to</strong> 0.016" instead of the earlier 0.012". On the sameengines the sump had yet <strong>an</strong>other modification, as oil had <strong>be</strong>en backing up at thelonger forward end under braking. So a longer oil pick up was fitted. As it was heavier,it had four bolts fixing it instead of two, <strong>an</strong>d these c<strong>an</strong> <strong>be</strong> seen on the nearside of thesump. Previous sumps should <strong>be</strong> so modified, if not already done.25) The oil level in the oil pump was raised <strong>to</strong> assist priming, the idea <strong>be</strong>ing that ifit remained full on draining the sump, it would self prime on starting the engine, ( butsee item 30.) This was on SC2/18120 <strong>an</strong>d TD2/26635.35

26) From SC2/18272 <strong>an</strong>d TD2/27551 the cr<strong>an</strong>kshaft was forged out of E.N. 100 <strong>to</strong>ncarbon steel, a stronger material, part num<strong>be</strong>r 168537. Had some TD’s broken a few ofthe old ones racing?27) At SC2/18122 on the YB only, the spark plugs were ch<strong>an</strong>ged <strong>to</strong> Champion N8,the N8B deleted.28) In Oc<strong>to</strong><strong>be</strong>r 1952 the Wolseley 4/44 with its version of the SC2 engine was inproduction, called the XPAW. Because of the new camshaft timings it was found thesprings could <strong>be</strong>come coil bound so the valve spring faces were reduced by 0.5mm onall ‘X’ series engines. This occurred at SC2/19037, TD2/27867, <strong>an</strong>d XPAW/1308. Headswill have <strong>be</strong>en swapped all over the place by now, but they will <strong>be</strong> round hole heads.This modification was done in early 1953, <strong>an</strong>d records show the SC2 engine ended at18460, rather odd!! The valve guides were now 24.5mm above the head.29) At TD2/281167 the rocker pillar bolts were drilled <strong>an</strong>d wire locked, as per normalaircraft <strong>an</strong>d racing practice. The 4/44 remained with spring washers, the YB hadgone, the ZA Magnette replacing it with its BMC 1489cc ohv by-pass oil filter engine.30) At last, by drilling a small air hole up inside the oil pump, the oil pump wasmade self priming. The TD had by now <strong>be</strong>en replaced by the TF so the Midgets suffixch<strong>an</strong>ged but the num<strong>be</strong>ring system continued on. This was at TF/31263 <strong>an</strong>d XPAW/5142. Ch<strong>an</strong>ging the oil was no problem, oil pressure was inst<strong>an</strong>t on starting upafterwards. Both the TF <strong>an</strong>d 4/44 had pressurised cooling systems, at all of 4psi.The TF 1250cc engine was infact the TD Mk2 slightly more powerful version, with<strong>an</strong> extra 4bhp over the st<strong>an</strong>dard TD unit. This block had <strong>be</strong>en recored <strong>to</strong> enable it <strong>to</strong> <strong>be</strong>bored out <strong>to</strong> 72mm, giving 1466cc, <strong>an</strong>d <strong>be</strong>coming the XPEG, the TF <strong>be</strong>coming the ‘TF1500’. The TF 1500 head was the TD2 one, with bigger valves, inlet 36mm, ( TD 33mm),exhaust 34mm, ( TD 31mm.)31) To reduce oil feed <strong>to</strong> the rockers, the b<strong>an</strong>jo-bolt at the oil gallery on the rockerfeed pipe, had its internal diameter reduced <strong>to</strong> 0.055". This was at TF/31493 <strong>an</strong>dXPAW/5300.32) On the 4/44 only, at XPAW/6809, the water outlet <strong>an</strong>gle at the thermostat wasch<strong>an</strong>ged <strong>to</strong> face the offside, in readiness for the BMC ‘B’ series <strong>to</strong> <strong>be</strong> fitted as theWolseley 15/50 ( 1500cc, 50bhp) radia<strong>to</strong>r was <strong>be</strong>ing fitted. This outlet looks just like aTF one <strong>to</strong> me, <strong>an</strong>d I suspect it was <strong>to</strong> commonise parts, as the 4/44 carried on for<strong>an</strong>other 23,000 cars!! Or was the ‘B’ series in short supply?33) Again, the 4/44 had a completely different sump casting <strong>to</strong> its M.G. cousins,with a floating oil pick-up. Air leaks had occurred, so it was improved with a four boltfixing instead of two. These c<strong>an</strong> <strong>be</strong> seen on the outside of the sump under the oil pump,from XPAW/7642.34) The TF had gone, the 4/44 the sole user of the ‘X’ series of engines, with the BMC‘A’ <strong>an</strong>d ‘B’ series taking over. On XPAW/20901 the timing chain oil thrower wasenlarged from 2.6" <strong>to</strong> 2.812" <strong>to</strong> try <strong>to</strong> reduce oil leaks at the front end.35) We are in<strong>to</strong> 1956, the front as<strong>be</strong>s<strong>to</strong>s rope seal on the cr<strong>an</strong>kshaft is replaced witha modern neoprene sprung lip seal, at XPAW/24110, part num<strong>be</strong>r AEG133, ( a Morris36

The Wolseley 4/44 1250ccengine for comparrison <strong>to</strong> theMG unit.37

The excellent full flow oil filter system of all XPAG/XPAW/XPEG 1250cc engines.38

part num<strong>be</strong>r, not BMC.) Sump <strong>an</strong>d timing cover were machined <strong>to</strong> suit, <strong>an</strong>d the sumpgasket modified. Watch out at au<strong>to</strong>jumbles you buy the right sump gasket for yourengine, the late 4/44 one is <strong>to</strong>o short at the front end, for your M.G.36) Last ‘X’ series engines off the line, Oc<strong>to</strong><strong>be</strong>r 1956 in a 4/44. The 4/44 r<strong>an</strong> for34,000 units, <strong>an</strong>d had just a few engine modifications, perhaps it was well sorted bythen. <strong>How</strong>ever the column ch<strong>an</strong>ge gearbox fitted with its selec<strong>to</strong>r rods entering thecasting under the oil level line, adapted from the YB, was <strong>an</strong>other s<strong>to</strong>ry. It leaked till theend. Both the TF <strong>an</strong>d 4/44 used the later cr<strong>an</strong>kshaft part num<strong>be</strong>r 168557.Known ‘X’ <strong>Engine</strong> Casting Num<strong>be</strong>rs.Casting num<strong>be</strong>rs, as already mentioned, are those of the pattern, <strong>an</strong>d sometimescarry through the system <strong>to</strong> <strong>be</strong>come a part num<strong>be</strong>r of the item in the spares book. But,if <strong>an</strong> item is modified after the casting of the item, such as threads ch<strong>an</strong>ging size, orholes <strong>be</strong>ing bigger, or similar, the actual pattern num<strong>be</strong>r will not ch<strong>an</strong>ge, but the partnum<strong>be</strong>rs on the spares list will, so <strong>be</strong>ware. Also, in later years when res<strong>to</strong>ring a car, <strong>an</strong>item may <strong>be</strong> used that was once a Morris/Wolseley part, <strong>an</strong>d you modify it <strong>to</strong> M.G.specification. There is nothing wrong in this, it is good use of otherwise scrap. I have‘cast’ octagons in Araldite from a mould made in plasticene, off a M.G. 24146 cylinderblock, <strong>to</strong> re-araldite <strong>to</strong> a Wolseley 4/44 168421 block. This was m<strong>an</strong>y, m<strong>an</strong>y years ago,<strong>an</strong>d I see its still on that engine, the owner none the wiser. I know others have also donethis. For the perfectionist though, only the right bit works.Model/ItemCasting Num<strong>be</strong>rEarly Morris/Wolseley Ten 1140cc ‘X’ cylinder block, oval, 22500Later post war 1140cc cylinder block, oval water holes, 24144Early M.G. 1250cc ‘X’ block, octagon cast in,oval water holes, 24146Later post war 1250cc M.G. block,octagon cast in,oval holes, 244454/44, later TD, & TF block, no octagon, round water holes, 168421Early 1140cc cylinderhead, no centre oil drain, oval water holes, 22812Later post war 1140cc head, same as early ‘T’ type, oval holes. 22952Later TD, & Y oval hole cylinder head, short reach plug, 229524/44, TD & TF head, round water holes, long reach plugs, 168422Late 4/44 head, round water holes, 168425Casting num<strong>be</strong>rs are often quite rough, the pattern getting knocked about with use<strong>an</strong>d age, num<strong>be</strong>rs c<strong>an</strong> <strong>be</strong> difficult <strong>to</strong> see. On the block it is under the tappet cover,<strong>be</strong>hind the dynamo, above the octagon if the block has one. See Block Identity. On thehead it is easy <strong>to</strong> see on the <strong>to</strong>p, though often not fully clear, casting ‘flash’ obscuring it.XPAG Camshaft Checking.This is the most import<strong>an</strong>t part of the engine in terms of perform<strong>an</strong>ce <strong>an</strong>d driveability,though good cylinder head design does help. As years pass, people modifytheir cars, or fit replacement items that have <strong>be</strong>en improved by the m<strong>an</strong>ufacturer. Oneproblem that often occurs is trying <strong>to</strong> decide which camshaft your XPAG has fitted,without stripping it down. M<strong>an</strong>y cars have the 0.012" clear<strong>an</strong>ce camshaft, but some still39

have the older 0.019" clear<strong>an</strong>ce version. By far the <strong>be</strong>st method I have seen was in theMGCC Safety Fast magazine, sent in by David Clark of Westminster, Vermont, USA. Itrelies on the fact that only the later cars had 5;45;45;5 cam timing, known as equaloverlap,or split-overlap if you speak Americ<strong>an</strong>. That is both inlet <strong>an</strong>d exhaust camhave the same timing, but in ‘mirror’ fashion. The earlier ‘T’ types had 11;57;52;24, veryun-equal. The first pair of num<strong>be</strong>rs read as inlet opens BTDC, closes ABDC, thenexhaust opens BBDC <strong>an</strong>d closes ATDC. The XPAG is not a quiet engine <strong>an</strong>yway, <strong>an</strong>done <strong>to</strong> worry about is one with no tappet clatter, as it is <strong>be</strong>tter <strong>to</strong> hear it th<strong>an</strong> not. In<strong>to</strong>days leadfree petrol age, no noise me<strong>an</strong>s the valves are pocketing, ie eating away theseats, <strong>an</strong>d closing up the clear<strong>an</strong>ce.If David Clark’s check is carried out, <strong>an</strong>d you decide you have a 12 thou cam, butperform<strong>an</strong>ce is awful, you actually have one of the mid-way 5;45;45;5 1140cc timed <strong>an</strong>dground camshafts, but with <strong>an</strong> 8mm lift at the valve for the M.G. 1250cc XPAG. Seemodification list. This cam still has a 0.019" tappet clear<strong>an</strong>ce. Conversely, running a0.012" cam at the 0.019" clear<strong>an</strong>ces sounds almost like a diesel engine.” I would like <strong>to</strong> share with you a cheap <strong>an</strong>d cheerful method for making <strong>an</strong>accurate determination of high verses low camshaft with your feeler gauge, ascrewdriver, <strong>an</strong>d a five-sixthteenths BSF sp<strong>an</strong>ner.Because of the equal overlap of the valve timing, of the 0.012" clear<strong>an</strong>ceXPAG 5;45;45;5, they are split evenly about <strong>to</strong>p-dead-centre ( TDC ) <strong>an</strong>d bot<strong>to</strong>m-deadcentre( BDC ). This is called split-overlap.Now, <strong>to</strong> check the valve timing, adjust the valves <strong>to</strong> the recommendedvalve clear<strong>an</strong>ce, in this case 0.012". Turn the engine on the starting h<strong>an</strong>dle until the f<strong>an</strong><strong>be</strong>lt pulley on the engine indicates TDC for num<strong>be</strong>r one cylinder, with the valvesROCKING. This me<strong>an</strong>s we are at the end of the exhaust stroke <strong>an</strong>d <strong>be</strong>ginning of theinlet stroke, with both valves partially open. At this TDC loosen the locknuts <strong>an</strong>d turnthe tappet adjusting screws all the way up <strong>an</strong>d then down again until there is exactlyno clear<strong>an</strong>ce at the valve. The valve will now <strong>be</strong> shut, <strong>an</strong>d the adjusting screw just<strong>to</strong>uching it. Now turn the engine one more cr<strong>an</strong>kshaft revolution ONLY, ( till you arenow at the <strong>to</strong>p of the compression stroke,) turn until the TDC marks on the pulley onceagain align exactly. Using your feeler guages measure the resulting valve clear<strong>an</strong>ce. Ifthe clear<strong>an</strong>ces match, you have a split-overlap camshaft, possibly with 0.012" design. Ifyou are out five <strong>to</strong> ten thou, with the differences <strong>be</strong>ing from keyway <strong>to</strong>ler<strong>an</strong>ces, etc, it isstill a split-overlap cam. If it is <strong>an</strong> earlier, or fast cam, the clear<strong>an</strong>ces will differ a lot.“Camshaft lo<strong>be</strong> design is a very precise art, <strong>an</strong>d the shape is very import<strong>an</strong>t. Morris& M.G. strove <strong>to</strong> get the <strong>be</strong>st with silence, but a compromise was the result. The .012"gap was it. The gap is part of the camshafts design <strong>an</strong>d has <strong>to</strong> do with the ‘ramp’ <strong>an</strong>d itsacceleration of the valve lifting gear. Stick <strong>to</strong> the clear<strong>an</strong>ces given.40

Model Cam Timings part num<strong>be</strong>r LiftSA 2 ltr Saloon, 11;59;56;24 8mmVA 1 1/2ltr Saloon, 11;59;56;24(later 11;57;52;24)8.4mmWA 2.6 ltr Saloon, 11;59;56;24 8mm1147cc 10hp engine 5;45;45;5 6.5mmTA Midget, 11;59;56;24 X24084,MG862/171,AAA57768mmTB & TC Midget, 11;57;52;24 8mmTD Midget 11;57;52;24 8mmTD after TD2/24116 5;45;45;5 AAA3096, 168553 8.3mmYA 1 1/4ltr Saloon 11;57;52;24 AAA3309, 168553 6.5mmYA after SC/16831 5;45;45;5 AAA3096, 168553 8.3mmYB 1 1/4 ltr Saloon 5;45;45;5 AAA3096, 168553 8.3mmTF 1250 & 1500 5;45;45;5 AAA3096, 168553 8.3mmWolseley 4/44 5;45;45;5 AAA3096, 168553 8.3mmhalf-race; 13;59;50;22-8.3mm AEG122 n/kfull race; 32;58;60;30-8.3mm AAA3095 n/kThe XPAG engine was also used by other sports car builders, in tiny qu<strong>an</strong>tities.People like Cooper <strong>an</strong>d Lotus put them in<strong>to</strong> their specialist cars, <strong>an</strong>d of course it wentracing in m<strong>an</strong>y forms, <strong>be</strong>ing capable of quite some development. Considering theengine was <strong>an</strong> improvement of <strong>an</strong> old Morris sv unit, the MPJM, in the Morris Tenseries ‘M’, the XPJM 1140cc 10hp version with just 37bhp, then <strong>be</strong>ing uprated for M.G.<strong>to</strong> 1250cc with either 46bhp or 54bhp, it is amazing <strong>to</strong> think that Syd Enever, MG’schief designer, obtained 213bhp at 7000rpm with a supercharged version, pushing a carup <strong>to</strong> 210mph, from the same simple XPAG! Outside specialists often offer tuningequipment for sportscar engines, <strong>an</strong>d <strong>to</strong>day the cross-flow alloy head for the 1798cc ‘B’series is on offer by Webcon Ltd in Middlesex giving 120bhp. In the 1950’s people likeLaystall also offered <strong>an</strong> alloy cylinder head for the XPAG, with polished larger ports<strong>an</strong>d bal<strong>an</strong>ced combustion cham<strong>be</strong>rs. More information of this type is in ‘Tuning <strong>an</strong>dMaintaing MG’s’, by Phillip H. Smith, Haynes.Distribu<strong>to</strong>rsThe Lucas distribu<strong>to</strong>rs fitted <strong>to</strong> the various ‘X’ series all look very similar, <strong>an</strong>d thelater items from the ‘A’ <strong>an</strong>d ‘B’ series c<strong>an</strong> <strong>be</strong> fitted. The correct part num<strong>be</strong>rs for theengines are; 40048 was for the TC, the 40162 for the early TD, 40368 after TD2/ 20942,40367 TF, <strong>an</strong>d 40058A for the smaller Morris Ten/4 series 3, <strong>an</strong>d the YA.Reconditioned <strong>Engine</strong>s (Traps for the unwary)Chapter Four goes in<strong>to</strong> identifying Morris <strong>Engine</strong>s, <strong>an</strong>d later BMC Gold Seal,reconditioned engines. The information on the engines data plate does not give all thes<strong>to</strong>ry. As mentioned earlier, parts that were faulty could <strong>be</strong> re-machined for use on areplacement engine. The part would <strong>be</strong> machined <strong>to</strong> fit the re-machined worn bit of theengine <strong>be</strong>ing reconditioned. So it is as well <strong>to</strong> note that components such as CamshaftFollowers c<strong>an</strong> <strong>be</strong> .010" oversize, something that has caught out a lot of owners building41

up a good engine from two units. Only a micrometer will tell you this information, <strong>an</strong>dthe fact that a +.010" follower will not go in<strong>to</strong> a st<strong>an</strong>dard hole! You c<strong>an</strong>not re-machine afollower, as the lo<strong>be</strong> end is hardend. To reclaim cylinder heads it is commonengineering practice <strong>to</strong> cut out the valve seats, <strong>an</strong>d press in steel inserts. Today wethink of this as modifying a cylinder head for unleaded simply <strong>be</strong>cause we now usehardend steel inserts. Such practices are as old as the ICE itself. This should not causeproblems, if your engine was once so repaired. Trouble will arise once the head is <strong>to</strong> <strong>be</strong>made leadfree, as the inserts put in all those years ago may now me<strong>an</strong> your head isuseless, ie, the holes are bigger th<strong>an</strong> present available inserts. It is also common <strong>to</strong> leavein the valve guides, <strong>an</strong>d ream them out <strong>an</strong>d press in phosphor-bronze liners forleadfree use.<strong>Engine</strong>ering practices are not always carried out as per at the fac<strong>to</strong>ry. I have seencylinder blocks with one bore ‘re-bored’ <strong>to</strong> +.020" bigger th<strong>an</strong> the others, <strong>an</strong>d a pis<strong>to</strong>nfitted <strong>to</strong> complete the job. Perhaps one pis<strong>to</strong>n scored a bore on <strong>an</strong> otherwise goodengine, <strong>an</strong>d fin<strong>an</strong>ces of the owner kept the job <strong>to</strong> ‘one rebore please’. On elderly carsthat have <strong>be</strong>en through the mill, you need <strong>to</strong> <strong>be</strong> very careful. Some very tidy lookingcars, even these days, hide some awful engineering bodge-ups. Only a few years ago Ilooked at a 4/44 engine for sale at £400, <strong>an</strong>d upon turing it over, there was very littlecompression on No.2 cylinder. The engine looked cle<strong>an</strong> <strong>an</strong>d in good condition. Oninvestigation, a past owner had removed No.2 push rod <strong>an</strong>d cam followers, <strong>an</strong>d theexhaust valve, <strong>be</strong>cause of a burnt out pis<strong>to</strong>n, <strong>an</strong>d no funds. Shiny paint will fool most,or as in my RAF service days, ” Bullshit Baffles Brains”. <strong>How</strong> true.Secondh<strong>an</strong>d BodgesAnother car I <strong>be</strong>came involved in, <strong>an</strong> <strong>an</strong>cient YB, had <strong>be</strong>en on the parade square forages for sale for £20, in 1970 at <strong>an</strong> RAF station in Morayshire. I spotted its owner oneday ‘servicing’ the engine. Then a mate asked me <strong>to</strong> go with him <strong>to</strong> check the car out. Itr<strong>an</strong> reasonably well, but I was very suspicious over the excellent oil pressure of 55psiconsidering the mileage <strong>an</strong>d general condition, <strong>an</strong>d that I had seen the car <strong>be</strong>ing‘serviced’ recently. It was sold for a reduced £15 <strong>to</strong> my mate, after I had <strong>to</strong>ld him of mysuspicions, <strong>an</strong>d I asked if I could check out a few things. He agreed, <strong>an</strong>d I found twowashers <strong>be</strong>hind the oil pump pressure relief valve spring, <strong>an</strong>d NO oil filter element inthe filter bowl. Removing the washers <strong>an</strong>d fitting <strong>an</strong> element dropped the hot pressuredown <strong>to</strong> 35psi. I replaced the grooved ball <strong>be</strong>aring in the relief valve, obtaining a ballfrom <strong>an</strong> old ball race, tapping it in hard <strong>to</strong> ‘seat’ it, <strong>an</strong>d we had 40psi, <strong>an</strong> honest oilpressure. Whilst the washers simply hid the engine’s wear, removing the filter elementwas stupid, as this would ruin the engine very quickly. The seller w<strong>an</strong>ted <strong>to</strong> get the oilpressure up on the gauge. Such bodges were ( <strong>an</strong>d still are,) common on old secondh<strong>an</strong>d cars. Do you like the prices of these cars? Shows my age, but you have <strong>to</strong> acceptthey were just old b<strong>an</strong>gers of their day then.As b<strong>an</strong>gers, old M.G.s in the 1960’s got little servicing. One friend r<strong>an</strong> such a car,<strong>an</strong>d never carried out tappet clear<strong>an</strong>ce adjustments. Eventually I bought the car fromhim, as he was posted overseas, <strong>to</strong> simply sell on again for profit. I could not quietenthe engine, it sounded like a diesel with the .019" st<strong>an</strong>dard gap. I reduced it <strong>to</strong> .012",with no ch<strong>an</strong>ge. I drove the car for a few days <strong>be</strong>fore selling it, just <strong>to</strong> sort out <strong>an</strong>yrunning faults, <strong>an</strong>d noted the perform<strong>an</strong>ce was awful, but it was a wreck. The lad whobrought it, ( for £15,) complained <strong>to</strong> me, so I promised <strong>to</strong> fix it if he paid for the bits. He42

‘X’ Series of <strong>Engine</strong>sThat fitted <strong>to</strong> the Wolseley 4/44, of 1952, was virtually the SC/2 engine of the MG YB.A similar engine, fitted <strong>to</strong> a MG YA, with a seperate oil filter.43

agreed. I eventually sourced the camshaft, it had two inlet lo<strong>be</strong>s that were virtuallynon-existent, hardly opening the valves at all. One new camshaft with eight followers,<strong>an</strong>d the car almost flew, <strong>an</strong>d was quieter. I still have the cam, <strong>an</strong>d often show it <strong>to</strong>people <strong>to</strong> prove that <strong>to</strong> miss oil ch<strong>an</strong>ges is false economy, as the filter was a solid lumpof gunge on replacing it. Years later I had a V8 with the same fault!XPAG Cylinder Head GasketsThe oval hole <strong>an</strong>d round hole head gaskets are <strong>to</strong> suit the types of cooling holes inthe head <strong>an</strong>d block. Elsewhere this is dealt with quite comprehensively, under‘Modifications during Production’, <strong>an</strong>d ‘Casting Num<strong>be</strong>rs. At the time the cars wereassembled, the ch<strong>an</strong>ge actually came on the YA at engine num<strong>be</strong>r SC2 17463, <strong>an</strong>d TD217969. With head swaps over the intervening years, you need <strong>to</strong> go by the castingnum<strong>be</strong>rs, or look at the holes themselves, <strong>to</strong> fit a suitable gasket.TUNING THE XPAGAs mentioned, this is not a tuning book. but theJune 1998 issue of the MGCCmonthly magazine, Safety Fast, for June 1998, on pages 7 <strong>to</strong> 14, reproduces the SpecialTuning booklet issued by MG for the XPAG engine. Back issues are on 01235 555552.44

Mo<strong>to</strong>r Trader Service Data No. 233 M.G. Midget series T.F.Components of the engine, showing cylinder block with push-rod cover <strong>an</strong>d breather, cylinder head, sump, <strong>to</strong>rquereaction link, oil pump, pick-up <strong>an</strong>d alternative oil filters, m<strong>an</strong>ifolds (note inlet bal<strong>an</strong>ce pipe), air cle<strong>an</strong>er, waterpump parts, thermostat housing <strong>an</strong>d bypass circuit, cr<strong>an</strong>kshaft <strong>an</strong>d timing drive, connecting rod <strong>an</strong>d pis<strong>to</strong>nassembly <strong>an</strong>d valve train.45

Chapter FourState of the Art of the XPAG <strong>Engine</strong>What is fitted <strong>to</strong> my MG?Archaeology of Replacement <strong>Engine</strong>s XPAGHere we go in<strong>to</strong> <strong>an</strong> area not well researched by the experts. The following notesinclude my own observations of engines in cars at M.G. meetings. Some owners wish<strong>to</strong> trace their block, <strong>to</strong> see if it is <strong>an</strong> original one, often a problem if a reconditioned unit.The first two sketches show the normal octagonal identity plate, with a disc at thecentre, found on early engines on the flywheel housing extension, (<strong>be</strong>ll housing,) <strong>an</strong>dafter SC/15405 <strong>an</strong>d TD/2985 on the offside front end of the block, under a core plug ona raised platform on the casting. Both are held on with just one rivet. The engines withthe num<strong>be</strong>r on the <strong>be</strong>ll housing have casting num<strong>be</strong>r 24146, <strong>an</strong>d those with it on theoffside, casting num<strong>be</strong>r 24445. On this last unit the oil filter mounting altered <strong>to</strong> threebolts. The block for the 4/44/ late TD/YB/TF is similar, with a dip stick lug adjacent,casting num<strong>be</strong>r 168421.The plates were of brass, with all common information stamped in from the back ofthe plate, <strong>to</strong> give raised letters <strong>an</strong>d figures, here “MG CAR Co. Ltd.” <strong>an</strong>d “No.” will <strong>be</strong>raised. Only the unique engine num<strong>be</strong>r was stamped in from the front, giving indentednum<strong>be</strong>rs. It is done quite neatly, though possibly by h<strong>an</strong>d. So the first sketch showsengine num<strong>be</strong>r 18415 that will <strong>be</strong> stamped in from the front. Above the brass octagonthe original engine num<strong>be</strong>r may <strong>be</strong> stamped again in<strong>to</strong> the block metal surface, thoughas the cast iron is hard it c<strong>an</strong> <strong>be</strong> difficult <strong>to</strong> see. In this sketch a raised platform is shownas on the later blocks. Some engines I looked at did not have the num<strong>be</strong>r repeated onthe casting. The plate will <strong>be</strong> held on by one central rivet, <strong>an</strong>d this same rivet securinga small disc with the engine type on. This again will <strong>be</strong> in raised letters, <strong>an</strong>d as shownis “TYPE XPAG SC2”, on a YB. The second sketch shows <strong>an</strong>other similar identificationplate, this time engine num<strong>be</strong>r 33006, on a “TYPE XPAG TD”. All examples here arefrom real existing vehicles. From this it c<strong>an</strong> <strong>be</strong> seen it is not hard <strong>to</strong> decide what <strong>an</strong>original engine is from, if it is fitted <strong>to</strong> the right vehicle, <strong>an</strong>d if it matches the Guar<strong>an</strong>teePlate on the dash. The problems arise when it is a ‘reconditioned unit’.If <strong>an</strong> engine is rebuilt by its owner, or his friend, nothing will <strong>be</strong> recorded on <strong>an</strong>yplate riveted <strong>to</strong> the engine. The engine will retain its identity. But, when it was done byusing <strong>an</strong> exch<strong>an</strong>ge engine, ie you send yours back <strong>to</strong> the fac<strong>to</strong>ry <strong>an</strong>d <strong>an</strong>other differentunit is fitted in exch<strong>an</strong>ge, Morris Mo<strong>to</strong>rs will give each a new identity. Because ofdem<strong>an</strong>d, a SC2 may not go out as one, but may <strong>be</strong> stamped up as a TD2, if for inst<strong>an</strong>cedem<strong>an</strong>d for TD engines is high. Each engine was given a new num<strong>be</strong>r. This time theplate was a square one replacing the M.G. octagonal one, still with embossed num<strong>be</strong>rs<strong>an</strong>d letters raised for all common information, except the num<strong>be</strong>r itself. The samecentral rivet held the disc at the centre with the type on, just as the original unit. SketchNo.3 shows the square plate <strong>an</strong>d disc, as <strong>an</strong> engine for a “TYPE XPAG TD”, with thenum<strong>be</strong>r B98546. The letters “REPLACEMENT ENGINE” with “No.” at the bot<strong>to</strong>mleave you in no doubt this is a recon-unit. Careful checking above may reveal the originalnum<strong>be</strong>r, in this case 13542, but was it a TD, YB,or a 4/44?Next <strong>to</strong> the new identity plate, just aft of it, ( <strong>an</strong>d further under the m<strong>an</strong>ifolds,) is thereconditioning plate, with bore <strong>an</strong>d cr<strong>an</strong>k sizes on. This has the firm’s name on,46

Archaeology of Replacement XPAG <strong>Engine</strong>sSketch One, normal`Y` typeXPAG SC2 engine identifyplate, No. 18415.Sketch Two, normal XPAGTD engine identify plate,for No. 33006.Sketch Three, Morris enginereplacement engine plate, for aXPAG TD, No. B98546.Old engine num<strong>be</strong>r above of 13542.47

Archaeology of Replacement XPAG <strong>Engine</strong>sSketch four, founded with sketch three,rivetted just aft of it , the reconditioningplate for Morris Mo<strong>to</strong>rs, with relev<strong>an</strong>tsizes.Sketch Five, the later BMC XPAGreplacement engine plate, no disc,just a num<strong>be</strong>rSketch Six, the reconditioning platefor the BMC identity plate, for C 78561,giving the sizes.48

“MORRIS MOTORS Ltd. REPLACEMENT ENGINE”, again embossed from the rearso in raised letters. Stamped in from the front by h<strong>an</strong>d will <strong>be</strong> the bore <strong>an</strong>d cr<strong>an</strong>k size.This plate is often brass, but some I saw were aluminium alloy, <strong>an</strong>d all were secured bytwo rivets, one each side. On sketch No.4 the “BORE SIZE .040” refers <strong>to</strong> the rebore sizeof the cylinders, <strong>an</strong>d “CRANK SIZE R2” <strong>to</strong> a .020" regrind of the cr<strong>an</strong>kshaft. I only eversaw R2 <strong>an</strong>d R4, indicating .020" <strong>an</strong>d .040" undersize cr<strong>an</strong>ks. The shop num<strong>be</strong>r mustrefer <strong>to</strong> just that, the place the engine was built up at Morris <strong>Engine</strong>s.Some blocks have no original num<strong>be</strong>rs stamped above the plates, on the laterblocks, <strong>an</strong>d often there was no central disc, indicating it may have <strong>be</strong>en a rebored ‘new’block, rejected from a new car, but satisfac<strong>to</strong>ry for a recon-unit. Or Morris were feedingin new unused blocks after the models using them ceased. I suspect the enginenum<strong>be</strong>rs on the recon-units are infact job num<strong>be</strong>rs, one in <strong>an</strong>d one out so <strong>to</strong>speak.....the fact that no bits were on it originally was me<strong>an</strong>ingless. They simplyassembled the next available block with the next available cr<strong>an</strong>k, then head, <strong>an</strong>d so on.After all it was only the camshafts that differed for a while, until the bigger XPEGvalves, <strong>an</strong>d siamesed bores. As long as the right head gasket was used <strong>to</strong> suit thecooling holes shapes in the various heads <strong>an</strong>d blocks, they could put <strong>an</strong> engine<strong>to</strong>gether. I saw one Morris <strong>Engine</strong>s replacement unit with the later oil pump <strong>an</strong>d filter,with the old oil feed holes from the pipes plugged up, <strong>an</strong>d oil filter clamp bolt holesunused.Sketch No.5 shows a plate I saw with no type disc, or original engine num<strong>be</strong>r. AsBMC <strong>to</strong>ok over it seems the central disc was not always fitted, just a square plate <strong>an</strong>dthe replacement engine information plate. BMC started up their GOLD SEALReplacement <strong>Engine</strong>/Gearbox scheme in 1958, which included the still reconditionedXPAG units, ( my YB has one from 1963.) Red or green paint gave way <strong>to</strong> lurid gold.The two plates ch<strong>an</strong>ged a little. The square plate in the old octagonal plate position wassimpler, as at sketch No.5. It had “REPLACEMENT ENGINE” embossed, held on byone rivet, <strong>an</strong>d the num<strong>be</strong>r underneath, here C78561, ( my engine again.) This plate isstill brass with the num<strong>be</strong>r h<strong>an</strong>d stamped from the front. The BMC recondition platethat sits <strong>be</strong>hind sketch No.5 is shown in sketch No.6. It has the same information as theMorris <strong>Engine</strong>s version, except their name is replaced by “BMC REPLACEMENTENGINE” embossed in, <strong>an</strong>d is of aluminium alloy. This information plate is again heldon by two rivets, but the shop num<strong>be</strong>r has <strong>be</strong>en replaced with what appears <strong>to</strong> <strong>be</strong> theengine part num<strong>be</strong>r, in my case as shown, ” AEG 22R”. This is a Morris part num<strong>be</strong>r, on<strong>an</strong> engine rebuilt by BMC in 1963!! On <strong>an</strong>other MG ‘Y’ type I looked at with a Gold Sealengine, its plate gave the part num<strong>be</strong>r of “AEG 12R AD.” A ‘short block’ reconperhaps? A short-block is the term for just a reconditioned cylinder block, less head <strong>an</strong>dflywheel. Anders Ditlev Clausager of BMIHT, Gaydon, tells me that from his records,the TF1250 had a new engine as part num<strong>be</strong>r “SA 2445/3”, a new half engine, ( ie shortblock) as “AEG 4“; <strong>an</strong>d for the TF1500 engine as “AEF 4” <strong>an</strong>d half engine as “AEF 21”.From my extensive past experience in aircraft engineering, <strong>an</strong>ything with <strong>an</strong> “R”suffix usually me<strong>an</strong>s a reconditioned unit. The BMC engine num<strong>be</strong>r plate is a littlelonger th<strong>an</strong> the Morris <strong>Engine</strong>s one, covering the area of the platform where the originalunits num<strong>be</strong>r would have <strong>be</strong>en. The reconditioning data plate is larger as well.There are other ways of giving a partial identity <strong>to</strong> a cylinder block, though fraughtwith detail difficulties. An engine without a bulge in its timing chain cover is a veryearly unit, pre XPAG 883, so no TB’s had a tensioner. If the water drain tap on theoffside of the block is central under the m<strong>an</strong>ifolds, then it is <strong>an</strong> early T series or YA unit.49

XPAG Cylinder Block Identityearly blocklater clampcasting num<strong>be</strong>r50

XPAG Cylinder Block Identitylater engine num<strong>be</strong>r platformthe Octagon51

By the YB it had moved <strong>to</strong> the forward end of the block under the front inlet port,possibly a SC2/TD2 block modification, casting num<strong>be</strong>r 168421? This casting num<strong>be</strong>rdoes have the Wolseley 4/44 dip stick boss, just under the engine num<strong>be</strong>r platform onthe off side, but I have seen this boss on earlier blocks with the central water drain tapin YA’s. After SC2/17293 <strong>an</strong>d TD2/14224, the oil pump had <strong>an</strong> integral filter. Thisme<strong>an</strong>s the oil pipe <strong>an</strong>d the filter strap bolt holes were left undrilled on the rearnearside. Bl<strong>an</strong>k bosses here <strong>an</strong>d you have one of these later blocks, 24445 or 168421. Ifthe water holes where the cylinder head bolts <strong>to</strong>, are round, its a post SC2/17463, TD2/17969, or you have a TD Mk2. You should <strong>be</strong> able <strong>to</strong> confirm this with the castingnum<strong>be</strong>r of 168421, <strong>an</strong>d no octagon under the dynamo.If the oil filter strap has only two bolts holding it <strong>to</strong> the block, you have a 24146block, pre SC/15405, TD/2985. At SC2/17670 <strong>an</strong>d TD2/20942 the distribu<strong>to</strong>r lost itslocking clamp <strong>an</strong>d gained a cotter bolt that is at the side of the distribu<strong>to</strong>r location. Ifyou c<strong>an</strong> make out the original engine num<strong>be</strong>r stamped in<strong>to</strong> the <strong>be</strong>ll housing on earlyengines or above the platform on later units, this will deny or confirm your enginesorigin. Num<strong>be</strong>rs r<strong>an</strong> from 10001 <strong>to</strong> 18460 for the ‘Y’ series SC engines, <strong>an</strong>d from 501 <strong>to</strong>past 38500 for the ‘T’ series.Obviously one with a square plate with “WOLSELEY MO-TORS” on it <strong>an</strong>d a 4/44 dip stick hole should confirm its not <strong>an</strong> M.G. engine, thoughwith a sump swap it will fit one. At au<strong>to</strong>jumbles, measure the bore, if a cylinder block ison sale, a 63.5mm will <strong>be</strong> a 1140cc Morris/Wolseley block, confirm this by checking itscasting num<strong>be</strong>r, ( see Casting Num<strong>be</strong>rs.) Even so, a 1140cc c<strong>an</strong> <strong>be</strong> bored out <strong>to</strong> 1250cc.Block Identity XPAGThe first sketch is the early cylinder block with the distribu<strong>to</strong>r located by a clamp,the clamp held on<strong>to</strong> the block by one bolt, its threaded hole central <strong>to</strong> the boss thatholds the distribu<strong>to</strong>r shaft. Also shown is the early two bolt oil filter strap bracketfixing. See the descriptions <strong>an</strong>d modifications section.The second sketch (none are <strong>to</strong> scale), shows the later distribu<strong>to</strong>r fixingarr<strong>an</strong>gement using a cotter bolt. Its hole is offset <strong>to</strong> the shaft’s centre line. The three boltfixing for the wider oil filter clamp is also shown. Again see modifications.Both the first <strong>an</strong>d second sketches are of the ‘nearside’ of the cylinder block, as is thethird. This time the third sketch shows the location of the block casting num<strong>be</strong>r. It isactually under the dynamo, but you c<strong>an</strong> feel it with a finger, <strong>an</strong>d see it with a mirror ifyou do not w<strong>an</strong>t <strong>to</strong> remove the dynamo. It is well up under the tappet chest cover, <strong>an</strong>dmay <strong>be</strong> masked by the cork gasket edge, or good old oily dirt. If the cover is removed itc<strong>an</strong> easily <strong>be</strong> read.The fourth sketch shows the later engine num<strong>be</strong>r position <strong>an</strong>d the boss for theundrilled 4/44 dip stick hole. The SC2 <strong>an</strong>d TD2 blocks are said <strong>to</strong> carry the relev<strong>an</strong>tboss for the Wolseley 4/44 dip stick, on the front offside of the engine, the opposite side<strong>to</strong> the normal M.G. position nearside rear, actually shown in the first <strong>an</strong>d second sketch<strong>be</strong>hind the oil filter strap bolt holes. The M.G. exhaust pipe is very close <strong>to</strong> this, but onthe 4/44 the exhaust pipe goes out over the starter mo<strong>to</strong>r <strong>an</strong>d gearbox, so the area isquite free. The 4/44 hole is undrilled in the M.G. application, but as it is threaded it is asimple task <strong>to</strong> unscrew the pipe <strong>an</strong>d fit a bl<strong>an</strong>k.The last <strong>an</strong>d fifth sketch is that of the M.G. octagon found on the early blocks, ( seemodifications,) <strong>an</strong>d again this lives under the dynamo, rather hidden for <strong>an</strong>y effect.52

J<strong>an</strong>uary 1950 saw the XPAG 1250cc engine fitted <strong>to</strong> the TD Midget. The unit was virtually unch<strong>an</strong>ged fromthat fitted <strong>to</strong> the TC <strong>an</strong>d was a twin carburetter version of the 1 1/4 litre saloon. Just look at all lovely accessspace with old type winged bonnets. Drawing copyright is that of Au<strong>to</strong>car magazine.53

Both casting num<strong>be</strong>rs 24146 <strong>an</strong>d 24445 have the M.G. octagon cast in. If it is <strong>an</strong>y othernum<strong>be</strong>r, you might have found my, or <strong>an</strong>others, ‘addition’. See XPAG CastingNum<strong>be</strong>rs.The XPAG/XPEG/XPAW is <strong>an</strong> early ohv design. It does wear <strong>an</strong>d generates a goodold clatter, especially in .019" tappet clear<strong>an</strong>ce guise. Oil feeds <strong>to</strong> the valve gear need <strong>to</strong><strong>be</strong> kept clear, <strong>an</strong>d worn parts replaced as required. Short journeys will ruin the rocker’shollow shaft very quickly. Worn rocker pads c<strong>an</strong> <strong>be</strong> built up with special weld that c<strong>an</strong><strong>be</strong> hardend, some firms do a replacement/exch<strong>an</strong>ge service. Cam-followers also wearbadly, as c<strong>an</strong> the camshaft lo<strong>be</strong>s, leaving little lift but a noise like a diesel engine.NOTE that the ‘round hole’ block distribu<strong>to</strong>rs have a 1/8" spacer under them.Future of the XPAG?If the merger of BMC had not taken place, the XPAG would have <strong>be</strong>en fitted <strong>to</strong> thethen new M.G. ZA Magnette, possibly in its XPEG 1566cc form with 63bhp. TheWolseley did get the 1250cc version in the Gerald Palmer designed 4/44 of 1952, but asa nice new engine was in the offering, the ‘Z’ was delayed a little <strong>to</strong> 1953 <strong>to</strong> gain it.The ‘X’ series of Morris engines served M.G. very well indeed, <strong>an</strong>d was tuned bym<strong>an</strong>y owners <strong>to</strong> well above its designed power limits. It was indeed a <strong>to</strong>ugh little unit,evolved out of a long line of saloon car engines, not exactly designed. Of all the enginesused by M.G. it must <strong>be</strong> the <strong>be</strong>st known world wide, closely followed by theeverlasting BMC ‘B’ series. A whole industry now exists <strong>to</strong> cope with the classic carmarket, much of it includes those models powered by the XPAG.Morris actually went back <strong>to</strong> sv engines for the Cowley, the 10hp post warreplacement of the Series ‘M’. It was not until 1956 that the model saw the 1200cc ‘B’series. The Oxford has the 1498cc ‘B’ series, but M.G. got there first with its new saloonin 1953, see ‘Z’ Magnette.54

The Morris Minor (Series II) <strong>Engine</strong> LubricationThe early by-pass oil filter system of the 803cc ‘A’ Series, improved on the 948cc MG.55

Chapter FiveAUSTIN & MORRIS MERGE 1953-1981Austin <strong>Engine</strong>s in M.G.sBMC ‘A’ SERIES IN M.GPotted His<strong>to</strong>ryBy the time a M.G. model had <strong>an</strong> ‘A’ series under its bonnet in 1961, the engine wasquite old, <strong>be</strong>ing a scaled down version of the 1947 Austin A40 1200cc unit, the sameengine that was scaled up for the 1489cc ‘B’ series. To the eye both the ‘A’ <strong>an</strong>d ‘B’ seriesare obviously of the same family, <strong>an</strong>d are Austin designs. The design was the brainchild of Bill Appleby, Eric Bareham <strong>an</strong>d Jimmy Rix, whose job it was <strong>to</strong> provide a new,small, compact power unit for the new Austin Seven <strong>to</strong> <strong>be</strong> released in May 1952. TheA30 was a clever design in itself, using stressed skin like <strong>an</strong> aircraft, with a monocoquehull. The tiny ohv engine that eventually arrived was of only 803cc, ( BMC type 2A,)having hit the drawing board in 1947. Austin termed it the AS3 engine, ( AS3 <strong>be</strong>ing thecode for the A30,) or the 7hp unit. It had a bore of 58mm with a stroke of 76mm, <strong>an</strong>dshared components with its bigger brother the BMC ‘B’ series, such as starter mo<strong>to</strong>r,distribu<strong>to</strong>r, dynamo, cr<strong>an</strong>kshaft timing sprocket, camshaft sprocket, the cover, <strong>to</strong>name a few. With the later much bigger ‘C’ series it shared the timing sprockets, with aduplex chain. Later items like camshaft followers would <strong>be</strong> commonised, on all threeengine types,( you might call these bucket type followers.) The cylinderhead wasdeveloped by consult<strong>an</strong>t Harry Weslake, with a heart shaped combustion cham<strong>be</strong>rleading <strong>to</strong> more efficient burning of the mixture.The type 2A engine was not known as the ‘A’ series initially, not until the ‘B’ seriesarrived in 1953, <strong>an</strong>d the ‘A’ was <strong>to</strong> <strong>be</strong> fitted <strong>to</strong> other small saloon cars as well as the littleAustin A30 Seven.All the electrical items were one side of the engine, <strong>an</strong>d the m<strong>an</strong>ifolds the other,keeping fuel away from sparks. An unusual item was the method of driving the oilpump, <strong>an</strong>d still causes some people <strong>to</strong> <strong>be</strong> surprised when they remove the sump, asthey c<strong>an</strong>not see <strong>an</strong>y visible signs of <strong>an</strong> oil pump. It is not until the flywheel is removeddoes one see the oil pump under a cover on the tail end of the camshaft. This pump wassatisfac<strong>to</strong>ry until Alex Issigonis put the ‘A’ series gearbox in<strong>to</strong> its sump, for the Mini in1959, ( type 8A for Austin, 8MB for Morris engine.) The oil filter was well ahead of itstime as a screw on/off c<strong>an</strong>ister, but was only in a by-pass system. This me<strong>an</strong>s it bled oilfrom the main feed, filtered it, then dropped it in<strong>to</strong> the sump, this was <strong>to</strong> <strong>be</strong> improvedlater, <strong>to</strong> a full flow. The cylinder head had only five ports, only No.1 <strong>an</strong>d No.4 cylindershaving a single port for their exhausts. The inlets were siamesed as was the two centreexhausts. For the use the engine was <strong>to</strong> <strong>be</strong> put <strong>to</strong>, this was ideal, but those two middleexhaust valves could have a rough <strong>an</strong>d hot time, so only the <strong>be</strong>st steel was used. Cheapreplacements would burn out eventually. It was <strong>to</strong> have had <strong>an</strong> aluminium cylinderhead, <strong>an</strong>d some development engines were so fitted, but the production engines weregrey cast iron, as was the cylinder block. To keep costs down further, the timing chaincover, the sump, <strong>an</strong>d the rocker cover were all pressed steel stampings. The early small56

‘A’ series camshaft runs direct in the cast iron of the cylinder block, only the front<strong>be</strong>aring has a white metal lined steel backed <strong>be</strong>aring. The first engine r<strong>an</strong> in <strong>an</strong> A30pro<strong>to</strong>type in Novem<strong>be</strong>r 1950, <strong>an</strong>d performed very well, with its 7.2 <strong>to</strong> 1 compressionratio, producing 28bhp at 4,800rpm, hence A30!. <strong>How</strong>ever, further tests showed thethree cr<strong>an</strong>kshaft main <strong>be</strong>arings were <strong>to</strong>o small so were increased in diameter for theproduction engine. The steel flywheel with a dry clutch, was secured <strong>to</strong> the cr<strong>an</strong>kshaftwith four bolts. An ohv engine in a small mass produced car was very up <strong>to</strong> date forAustin, who were very conservative normally. Morris still had their USHM 918cc svunit in the Morris Minor ‘MM’. Ford were <strong>to</strong> carry on using their 10hp 1172cc sv for<strong>an</strong>other ten years, <strong>an</strong>d Hillm<strong>an</strong> their 1265cc sv until 1955. The 803cc engine was alsoput in<strong>to</strong> the heavy Morris Minor series 2, as the APHM, where it had its work cut out,in July 1952.The Austin Empire was different <strong>to</strong> the Nuffield ( Morris) one, Austin hadeverything made in-house at Longbridge, <strong>an</strong>d used few outside contrac<strong>to</strong>rs. They weremore of a big firm, where as Morris had lots of small ones dotted all over the country.The merger in 1952 was inevitably <strong>an</strong> Austin led one, <strong>an</strong>d they controlled the BMCEmpire, via one Leonard Lord, ex-employee of Morris. (Another s<strong>to</strong>ry)In 1956, along with a general tidy up <strong>an</strong>d updating of the whole BMC r<strong>an</strong>ge, the ‘A’series grew <strong>to</strong> 948cc, the famous size that gave the Morris 1000 the ‘1000’ name (typeAPJM or 9M). The unit was <strong>to</strong>ughened up somewhat, the spindly cr<strong>an</strong>kshaft of the 803had big ends of just 1.43"dia. These were now 1.625" diameter. The 1.75" main <strong>be</strong>aringswere the same. A35, A40, <strong>an</strong>d Morris 1000 had this unit, that the first Sprite was <strong>to</strong> seelater. The 803 <strong>an</strong>d 948cc had very strong, but expensive, cast malleable iron rockers,<strong>an</strong>d these gave way <strong>to</strong> pressed steel heavier, but cheaper, items with the arrival of the1098cc engine. The 803 <strong>an</strong>d 948 used a pinch bolt on its pis<strong>to</strong>n gudgeon pins, a cheapsystem dating <strong>to</strong> <strong>be</strong>fore the XPAG Morris unit.One wonders if they ever realised when the first little A30 rolled off the productionline, that the ‘A’ series was <strong>to</strong> <strong>be</strong> so import<strong>an</strong>t <strong>to</strong> Austin, then BMC, BMH, BL, AustinMorris, Austin Rover, <strong>an</strong>d finally Rover, including such cars as the A30, A35, A40Farina, Morris 1000, Austin Healey Sprite, M.G. Midget, 1100/1300 fwd, Allegro, Mini,Marina, Metro, <strong>an</strong>d the smaller Maestro <strong>an</strong>d Montego. From 1952 till 1990, 38 years.Our interest is in the first ‘A’ series that M.G. used, in the Midget of 1961, <strong>an</strong>d thefront wheel drive ADO16 1100/1300 M.G’s of 1962, <strong>an</strong>d the ‘A’ Plus units in the muchlater M.G. Metro, of 1982. Before we look at these units, just soak up the massive useBMC put the engine <strong>to</strong> in the following list.**Note that the BMC engine num<strong>be</strong>ring chart following applies <strong>to</strong> all the BMCfamily of engines, A, B, <strong>an</strong>d C, series. For ‘A Series’ tuning, buy the book Tuning BL ASeries by David Vizard, ISBN 0 85429 414 7. It is heavy with masses of good technicalinformation.57

ENGINE NUMBERINGBMC System for both ‘A’, ’B’ & ‘C’ series enginesWhilst the Morris <strong>Engine</strong>s system carried on for a while under BMC, BMCdeveloped their own as <strong>be</strong>low by 1956.Capacity Make Type Ancillaries Comp8, 803cc A, Austin A <strong>to</strong> Z A, Au<strong>to</strong>matic H, high comp9, 948cc M, Morris M, M<strong>an</strong>umatic L, low comp10, 1098cc W, Wolseley P, police spec12, 1275cc B, BMC industrial U, central gear ch<strong>an</strong>ge15, 1489cc G, M.G. O, overdrive,16, 1588cc H, special, N, column ch<strong>an</strong>ge,16, 1622cc J, Commercial,18, 1798cc R, Riley,22, 2200cc V, V<strong>an</strong>den Plas,25, 2500cc26, 2600cc,29, 2912cc.In the ‘B’ series, the Type-“A <strong>to</strong> Z” part is shown well under the MGB, that usedm<strong>an</strong>y variations. The first MGB’s were 18G, but as modifications were fitted, they<strong>be</strong>came 18GA, 18GB, 18GC, etc. See MGB section for more. The ‘A’ series did not sufferthe same North Americ<strong>an</strong> m<strong>an</strong>ia for emission controls of various types, so had far less‘types’ per model, often as few as only two.USE OF THE ‘A’ SERIESCar Model <strong>Engine</strong> cc. Prefix Num<strong>be</strong>r .Austin A30 803cc 2AAustin A35 948cc 9AAustin A35 V<strong>an</strong>, (optional) 848cc 8AG ( post 1962, most GPO.)Austin A40 mk1 948cc 9A or 9DAustin A40 mk2 948cc 9DBAustin A40 mk2 1098cc 10D or 10DDAustin Healey Sprite mk1 948cc 9CG or 9CCSprite Mk2/ M.G. Midget mk1, 1098cc 10CGSprite mk3/ Midget mk2 1098cc 10CC ( 2" main <strong>be</strong>arings.)Sprite Mk4/ Midget mk3 1275cc 12CC or 12CE home marke<strong>to</strong>r12CD or 12CJ N.Americaafter Oct. ’72 12V/586F/H home marke<strong>to</strong>r12V/671Z/L N. AmericaAustin Allegro 1275cc 12H ( same as Metro)Austin Mini 848cc 8AMorris Mini 848cc 8MBAustin/Morris Mini after ’62 848cc 8AMAustin/Morris Mini au<strong>to</strong>matic 848cc 8AHfloor ch<strong>an</strong>ge,closed circuit breather8AJ58

The Morris Minor 803cc ‘A’ series of 1954, enlarged <strong>to</strong> 948cc in 1956.59

au<strong>to</strong>matic, closed circuit breather8AKMini GPO saloon & v<strong>an</strong>, 848cc 85H restric<strong>to</strong>r in carb.Mini Clubm<strong>an</strong> 1098cc 10HMini 1000 / Metro 1 litre 998cc 99HMini 1000 au<strong>to</strong>matic 998cc 9AGMini 1275 GT 1275cc 12HMini Moke 848cc 8ACWolseley Hornet/Riley Elf mk1 848cc8WRWolseley Hornet/Riley Elf mk2 998cc 9WRMini Cooper 997cc & 1070cc(S) 9F/SA/H 9:1 compMini Cooper 997cc 9F/SA/L 8:3 compMini Cooper 970cc (S) 9F/SA/X 10:1 compMini Cooper 1275cc (S) 9F/SA/Y 9.75:1 compMini Cooper 998cc 9FA/SA/H 9:1 compMini Cooper 998cc 9FA/SA/L 8:3 compMini Cooper 970cc (S) 9FC/SA/H 9:1 compMini Cooper 998cc 9FD/SA/H 9:1 compMini Cooper 1070cc (S) 9FD/SA/H 9:1 comp(engine 33661 <strong>to</strong> 33948)Mini Cooper 998cc 9FD/SA/L 8.3:1 compMini Cooper 970cc (S) 9FD/SA/X 10:1 compMini Cooper 1275cc (S) 9FD/SA/Y 9.75:1 compMini Cooper 970cc (S) 9FE/SA/X 10:1 compMini Cooper 1275cc (S) 9FE/SA/Y 9.75:1 compMini Cooper 1070cc (S) 10F 8.3:1 compMorris Minor series 2 803cc APHM, (Morris num<strong>be</strong>ring)Morris Minor 1000 s3 948cc APJM, ch<strong>an</strong>ging <strong>to</strong>....Morris Minor 1000 s4 948cc 9M in 1956.Morris Minor 1000 s5 1098cc 10MAMorris Minor 1000 s5 closed circuit breather10MEMorris GPO v<strong>an</strong> 948cc 8AG post 1962Morris 1000 V<strong>an</strong> 1098cc 10AB low compressionMorris 1000 V<strong>an</strong> closed circuit breathing10VGold Seal exch<strong>an</strong>ge for all in-line ‘A’ series8GAustin,Morris,Wolseley 1100 1098cc 10AMW, 10H.Austin,Morris,Wolseley 1100 1098cc Au<strong>to</strong>matic 10AGfloor ch<strong>an</strong>ge closed circuit breather10AHau<strong>to</strong>matic, closed circuit breather10AJM.G. 1100 Mk1 & Mk2 1098cc 10GRRiley 1100 1098cc 10GRV<strong>an</strong>den Plas 1100 1098cc 10GR or 10VM.G. 1300 Mk1 1275cc 12GM.G. 1300 Mk2 1275cc 12GR after April ’68.Riley 1300 1275cc 12GR1300 fwd Au<strong>to</strong>matic 1275cc 12AV<strong>an</strong>den Plas 1300 1275cc 12GR or 12VMarina 1300 1275cc 12VAustin 1300 ‘S’ mk1 & mk2 1275cc 12FAAustin 1300 ‘S’ mk3 1275cc 12H**Unleaded Austin Metro 1.3 engines; 12H/E24, 35, 39, 40, 41, 42, 67 up <strong>to</strong> 75.60

MG Midget Mk 1 `A`Series , first MG <strong>to</strong> use this engineCutaway view of the basic engine.This is the ‘A’ Series in itsversion as fitted <strong>to</strong> the 948cc MG Midget Mk1/Sprite Mk2. Notice the lightweightbucket cam-followers that the ‘B’ series would adopt in 1964 in the five main <strong>be</strong>aring 1798cc engine. Also theinfamous water by-pass hose <strong>be</strong>tween the head <strong>an</strong>d block by the thermoostat, deleted on the’A’ Plus engines. Thisengine has the later exhaust m<strong>an</strong>ifold with no bl<strong>an</strong>king plate for the 803cc Zenith carburetter hot spot.61

Marina V<strong>an</strong> 1.1 1098cc 10VMarina V<strong>an</strong> 1.3 1275cc 12V low compressionMarina Ital 1275cc ‘A’ plus 12VMetro 1 litre 998cc ‘A’ plus 9HAustin Metro 1300 1275cc ‘A’ plus 12H/DM.G. Metro 1300 1275cc ‘A’ plus 12H/D24M.G. Metro 1300 leadfree 1275cc ‘A’ plus 12H/F01M.G. Metro 1300 Turbo 1275cc ‘A’ plus 12H/F01Austin Metro Sport 1275cc ‘A’ plus 12H/F02Austin Metro GTa 1275cc ‘A’ plus turbo 12H/F02Austin/Rover Metro 1.3 1275cc ‘A’ plus 12H/F **Austin Maestro 1300 1275cc ‘A’ Plus 12H ( Marina typesump & oil filter)After about 1970 BMC/BL had reduced the prefix <strong>to</strong> just the engine size <strong>an</strong>d itsalignment in the car, ie ‘V’ me<strong>an</strong>t vertical for rwd, <strong>an</strong>d ‘H’ me<strong>an</strong>t horizontal for fwd.Using the engine num<strong>be</strong>ring <strong>an</strong>d fitment charts, you should find that a M.G.Midget with a 1098cc engine with a prefix of ” 10CG/U/H/ ” has <strong>an</strong> early 1098cc smallmain <strong>be</strong>aring unit, ( made <strong>be</strong>tween Oc<strong>to</strong><strong>be</strong>r 1962 <strong>an</strong>d March 1964, ) with a central floorgearch<strong>an</strong>ge, of a high compression ration, ( ie 9 <strong>to</strong> 1, the lower 8.3 <strong>to</strong> 1 <strong>be</strong>ing optional foroverseas.)The ‘A’ Series Through The Years.Model year cc bhp @ rpm <strong>to</strong>rque comp type bore/strokeAustin A30 1952 803 28 @ 4800 40 lb/ft 7.2 2A 58mm/76mmAustin A35 1955 948 34 4750 50 8.3 9A 63 by 76Austin A40 mk1 1958 948 37 4750 50 8.3 9D,9DB 63 by 76Austin Mini 1959 848 34 5500 44 8.3 8A,8MB 63 by 68Austin A40 mk2 1961 1098 47 5100 60 8.3 10D 64.5 by 84MG Midget mk1 1961 948 46 5500 55 8.3 9CC 63 by 76Mini Cooper 1961 997 55 6000 9 9F 63 by 81MG Midget mk1 1962 1098 52 5500 57 8.9 10CG 64.5 by 84MG 1100 1962 1098 55 6000 61 8.9 10GR 64.6 by 84Mini Cooper 1963 1071 70 6000 62 9 9F 70.5 by 68MG Midget mk2 1964 1098 59 5700 60 8.9 10CC 64.5 by 84Mini Cooper 1964 1275 76 5900 79 9 9F 70.5 by 81MG Midget mk3 1966 1275 65 6300 65 9 12CC,12V 70.5 by 81MG 1300 1969 1275 70 6300 70 9.97 12G, 12GR ..Marina 1.3 1971 1275 65 5750 65 8.8 12V ..Morris Ital ‘A’ plus 1980 1275 67 5750 69 8.8 12V ..MG Metro 1300 1982 1275 72 6000 73 10.5 12H ..MG Metro Turbo 1982 1275 93 6150 85 9.4 12H ..28bhp <strong>to</strong> 93 bhp in 30 years, from 803cc <strong>to</strong> 1275cc, 4800 rpm <strong>to</strong> 6150rpm, thats someimprovement. Excellent <strong>to</strong>rque figures ( turning force,) as well, 40 lb/ft <strong>to</strong> 80 lb/ft, thisgives a <strong>be</strong>tter picture as it is this mid r<strong>an</strong>ge power which is used for acceleration <strong>an</strong>d<strong>to</strong>p gear perform<strong>an</strong>ce. Note that eight M.G. models used this engine.A point of difference <strong>be</strong>tween ‘A’ series is the method of driving the oil pump fromthe rear of the camshaft. At first there was a pin drive, then a slot drive, <strong>an</strong>d in the later62

1275cc a spider drive. The slot drive has two pumps, the 1275c has a longer nose as theblock is thicker. To make life easy, the num<strong>be</strong>rs of bolts holding them on differ. Anotherpoint is that all except the 1275cc engine have diagonally split big ends, so the con rodc<strong>an</strong> <strong>be</strong> withdrawn up through the bore. The 1275cc has horizontally split big-ends, astronger design, as the bore is bigger <strong>an</strong>d allows removal. Bearing shell lining materialdiffers depending upon the use the engine is put <strong>to</strong>. M.G. use steel backed copper-leadalloy, later lead-indium, as the <strong>be</strong>aring lining. Compression ratios were easy <strong>to</strong> swapabout on the ‘A’ <strong>an</strong>d the ‘B’ series, as this was controlled by the pis<strong>to</strong>n crown height, allthe cylinderhead combustion cham<strong>be</strong>rs capacity within that model r<strong>an</strong>ge <strong>be</strong>ing thesame.M.G. Fit the ‘A’ Series <strong>to</strong> a Sports Car.M.G. Midget Mk1 <strong>Engine</strong>, ( 1961-62)This is a bit of a lie, as it was Austin Healey who first did it within BMC, using theA30/35 suspension, gearbox <strong>an</strong>d rear axle, the 948cc ‘A’ series engine with twin 1 1/8"SU HS1 carbs, useless wire-mesh p<strong>an</strong>cake air filters, Morris Minor rack <strong>an</strong>d pinionsteering <strong>an</strong>d full hydraulic brakes. ( The A30/35/40 mk1 had awful hydraulic-frontbrakes, with cable-rear brakes.) The 948cc engine ( 9CC) was little ch<strong>an</strong>ged from theMorris Minor/A40 unit, even down <strong>to</strong> the st<strong>an</strong>dard BMC cam timings of 5;45;45;5 with.312" lift at the valves, but the compression ratio was raised from 8.3 <strong>to</strong> 1 <strong>to</strong> 9 <strong>to</strong> 1producing 43bhp at 5200rpm. The easier breathing engine, <strong>an</strong>d the rev limit raisedfrom 4750 in the Minor/A40 <strong>to</strong> 5200 in the Austin Healey Sprite Mk1 of 1958 gave theextra 9bhp, ( 34bhp in the saloons,) giving the Frogeye good perform<strong>an</strong>ce in its day.There were also stronger valve springs <strong>to</strong> allow higher revving, with stellite facedexhaust valves <strong>an</strong>d harder copper/lead main <strong>be</strong>aring shells. The Healey designedchassis-less body was light <strong>an</strong>d strong, ( <strong>an</strong>d a bit short for people like me of 6ft & over.)The A30/35/40 legacy carried on its four bolt secured flywheel, <strong>an</strong>d its exhaustm<strong>an</strong>ifold, it was the same item, with the hot-spot for the Austin’s Zenith singlecarburetter bl<strong>an</strong>ked off. To fit the ‘A’ series in<strong>to</strong> the engine bay, the engine oil filter had<strong>to</strong> <strong>be</strong> raised by 1", or it sat on the offside chassis leg. There is a plate <strong>be</strong>tween the filter<strong>an</strong>d housing <strong>an</strong>d the block <strong>to</strong> accommodate this 1" rise. In 1956 the 948cc ‘A’ series hadgained a full-flow oil filter at last, using a similar ( Unipart GTE103,) throw awaypaper/felt element the later XPAG <strong>an</strong>d ‘B’ series used. Now all the oil went through thefilter <strong>be</strong>fore it arrived at <strong>an</strong>y <strong>be</strong>arings, something all ‘X’ series engines had done from1936. The camshaft had a shell <strong>be</strong>aring on all three journals now, on the 948cc engines;<strong>an</strong>d these, <strong>an</strong>d those on the cr<strong>an</strong>kshaft, needed <strong>be</strong>tter filtration, <strong>be</strong>ing unable <strong>to</strong> absorbtiny bits as white metal does. All M.G. cars using the ‘A’ series have stronger springs inthe oil pressure relief valve. The 948cc cars had a 6 1/4" clutch. The Mk1 sprite had inletvales of 1.09" diameter, <strong>an</strong>d exhaust valves of 1" diameter.By 1961 M.G. <strong>an</strong>d Healey had got <strong>to</strong>gether as the Sprite was <strong>be</strong>ing assembled atAbingdon, <strong>an</strong>d the engine gained a <strong>be</strong>tter 63mm bore by 76mm stroke, 948cc unit(9CG,) with <strong>an</strong> improved camshaft <strong>an</strong>d bigger SU HS2 1 1/4" carbs, with a properlydesigned cast iron exhaust m<strong>an</strong>ifold <strong>an</strong>d bigger alloy inlet m<strong>an</strong>ifold, with no hot-spot.Two nice large paper element air filters sat on the air intakes. The cylinder head gaineda bigger inlet valve, of 1.15" diameter, the exhaust remained at 1". The power went up<strong>to</strong> 52bhp, on a compression ratio of 8.9 <strong>to</strong> 1, ( optional 8.3) but as the new Mk1 MGMidget, ( released in June 1961,) with the similar Mk2 Sprite, putting on weight with <strong>an</strong>ew skin on its body, perform<strong>an</strong>ce was similar <strong>to</strong> the Frogeye.Note that M.G. used the63

prefix of a letter ‘C’ for the Midget engines, in 10CC or 10CG, not a ‘G’, as the fwdADO16 used <strong>an</strong> identical sized engine, it was the fwd car who used the 10’G’ prefix onits engine. ADO16 was about in 1960 in the ADO.M.G. Midget Mk 1 1/2 <strong>Engine</strong> (1962-64)The engine carried on the the Midget, but in Oc<strong>to</strong><strong>be</strong>r 1962 there was <strong>an</strong>improvement in the power, from a 1098cc windfall from the new 1100cc ADO16 frontwheel drive models recently introduced. This Midget is nicknamed the Midget Mk1 1/2. The Morris Minor <strong>an</strong>d the A40 Farina gained the new 1098cc ‘A’ series engine, butthis extra cc had <strong>be</strong>en gained by lengthening the stroke <strong>to</strong> 84mm with a small increasein the bore <strong>to</strong> 64.5mm. The main <strong>be</strong>arings were still those of the first A30 803cc 2Aengine, of 1.75" diameter. The big ends has <strong>be</strong>en enlarged <strong>to</strong> 1.652" in 1956 in the 948cc9M unit. In the staid saloon cars this did not matter, but it me<strong>an</strong>t the same engine in theharder driven Midget would have cr<strong>an</strong>kshaft problems, as this had not <strong>be</strong>enstrengthened at all, keeping the same size <strong>be</strong>arings. It was a long stroke unit withgreater reciprocating stresses for the poor cr<strong>an</strong>kshaft. The 1098cc unit with 8.9 <strong>to</strong> 1, (optional 8.1, ) with the same valves as the 948cc Midget, gave 56bhp in the Midget,47bhp in the saloons. There was also some internal comp<strong>an</strong>y competition, in that one ofthe new ADO16 models was a M.G. saloon, the MG 1100. Its 1098cc engine ( 10GR,) produced 57bhp, which was shared with the 1100 Riley Kestrel. It was from thesemodels the Midgets engine grew <strong>to</strong> 1098cc, BMC w<strong>an</strong>ting <strong>to</strong> keep the variations of the‘A’ as few as possible. The Midgets version <strong>be</strong>ing prefixed 10CG. The camshaft timingfor these engines was 5.45.51.21 still with .312" lift. To cope with the greater <strong>to</strong>rque, likethe saloons, the clutch grew from 6 1/4" <strong>to</strong> a 7 1/4" diameter. The <strong>be</strong>ll housing on thegearbox grew <strong>to</strong> accommodate the bigger clutch, <strong>an</strong>d also had ribs cast in<strong>to</strong> its casingfor strength. If you grind away the starter <strong>be</strong>ndix cover part of the earlier gearbox, <strong>an</strong>dcarry out a few trial fits <strong>to</strong> check for rubbing, the bigger clutch, with its flywheel, c<strong>an</strong> <strong>be</strong>fitted <strong>to</strong> earlier cars, with the ‘smooth’ gearbox. To fit a 1275cc engine <strong>to</strong> <strong>an</strong> early 1098ccMidget, using the earlier cars four bolt flywheel, will require it <strong>be</strong>ing drilled accurately<strong>to</strong> cope with the six bolts of the 1275cc cr<strong>an</strong>kshaft. Rather luckily the two holes left overwill locate on the 1275cc engines two dowels.M.G. Midget Mk2 <strong>Engine</strong> (1964-66)By March 1964 MG had convinced BMC <strong>to</strong> improve the Midget 1098cc engine, so itgained its own cylinder block, <strong>an</strong>d cr<strong>an</strong>kshaft from the Cooper ‘S’, now with 2" main<strong>be</strong>arings,( old size 1.75",) <strong>an</strong>d the Cooper 998cc cylinder head. So much for commonparts! This led the Midget <strong>to</strong> <strong>be</strong> called a Mk2, ( Sprite Mk3.) Austin had always usedmech<strong>an</strong>ical, engine driven off the camshaft, fuel pumps. The pump ch<strong>an</strong>ged <strong>to</strong> a SUelectrical one in the boot, <strong>an</strong>d the boss the mech<strong>an</strong>ical one used <strong>to</strong> occupy gained abl<strong>an</strong>king plate, ideal <strong>to</strong> bolt the tappet chest vent pipe <strong>to</strong>. The stronger engine has aprefix of 10CC, as well as a lip on the cr<strong>an</strong>kshaft boss for the flywheel <strong>to</strong> locate on. Theearlier Midgets <strong>an</strong>d the normal saloon rwd cars had flat faces for the flywheel <strong>to</strong> bolt<strong>to</strong>, using the outer edge of the cr<strong>an</strong>kshaft flywheel boss rim <strong>to</strong> locate on. It was in thefront wheel drive cars that the rotating v<strong>an</strong>e oil pump wore badly, as those tiny bits ofworn gears could <strong>be</strong> sucked up in<strong>to</strong> it, <strong>an</strong>d rapidly wear away the small v<strong>an</strong>es as theyrub<strong>be</strong>d around inside their aluminium alloy case. This led <strong>to</strong> Mini’s having lowpressure oil lights on at idle rpm, <strong>to</strong>o early in their lives. So the eccentric lo<strong>be</strong>d ro<strong>to</strong>rtype was fitted <strong>to</strong> the 1098cc engines throughout the r<strong>an</strong>ge, as this has a rolling motion,64

BMC ‘A’ SeriesNot <strong>an</strong> ‘A’ series, but that of the MG YB of 1952, with 1250cc.A MG Midget 1275cc ‘A’ series on sale at <strong>an</strong> au<strong>to</strong>jumble. Take care at such locations, the engine num<strong>be</strong>r prefixneeds checkingyouw<strong>an</strong>t the right unit.65

BMC ‘A’ SeriesThe Midget above has a Morris Marina ‘A Plus’ 1300 engine fitted, note the oil filter above the distributer.On the floor, a 1098cc Midget engine, on the box a Marina 1300 engine. Once built up, only the oil filter gives itaway.66

not rubbing, <strong>an</strong>d it lasts much longer. About now the North Americ<strong>an</strong> market haddictated <strong>an</strong> engine should ingest its own vent air <strong>an</strong>d fumes from the cr<strong>an</strong>kcase, so thefirst type of emission control was added. This consisted of a valve with a rub<strong>be</strong>rdiaphragm, that kept the cr<strong>an</strong>kcase just <strong>be</strong>low outside ambient air pressure, ventingin<strong>to</strong> the inlet m<strong>an</strong>ifold. If the diaphragm split, the engine could drink all its oil in ashort journey! This vent system needs a new oil filler cap, that allows <strong>an</strong> air bleedinwards <strong>to</strong> the rocker cover. All the 1098cc <strong>an</strong>d 998cc engines onwards had ridthemselves of the pinch-bolt gudgeon pin, now having fully floating pins, ( wrist-pin inAmerica.) The con-rod was thus much stronger, <strong>an</strong>d less likely <strong>to</strong> let go of a pis<strong>to</strong>n, wec<strong>an</strong> th<strong>an</strong>k the Coopers again, for this. 1964 was also the year the cable driventachometer was ch<strong>an</strong>ged <strong>to</strong> <strong>an</strong> electronic impulse type, whose innards were sharedwith the MGB <strong>an</strong>d Riley 4/72, <strong>an</strong>d later the Marina 1800TC.M.G. Midget Mk3 <strong>Engine</strong> (1966-74)The ADO16 needed more power, as did the now ageing Midget, so the ‘A’ serieswas redesigned as a 1275cc engine, ( 12CC or 12CE home market Midget,) for Oc<strong>to</strong><strong>be</strong>r1966, <strong>an</strong>d called the Mk3. The block was a lot stronger, the tappet chest covers weredeleted, <strong>an</strong>d the timing chain improved <strong>to</strong> a duplex,( two rows,). The bore was 70.5mmwith a stroke of 81mm, 2mm shorter th<strong>an</strong> the 1098cc engine. Camshaft timingremained at the 5;45;51;21 with a slight increase of lift <strong>to</strong> .318". Compression ratio was8.8 <strong>to</strong> 1, ( optional 8 <strong>to</strong> 1,) with bigger valves of inlet 1.3" <strong>an</strong>d exhaust of 1.15", giving65bhp, at 6300 rpm, the higher rev limit allowed by the shorter stroke,<strong>an</strong>d 65 lb/ft<strong>to</strong>rque at 3400rpm. That improved cr<strong>an</strong>kshaft of the 1098cc Midget, with its 2" main<strong>be</strong>arings, could cope with 1275cc power, but <strong>to</strong> <strong>be</strong> safe the big ends were enlarged <strong>to</strong>1.75", though the MG 1300 12G engine kept the 1.625" size for a while. A consequence ofexp<strong>an</strong>ding a 803cc design <strong>to</strong> 1275cc me<strong>an</strong>t the designed in safety margin grew less, thisis shown by the fact that the 1275cc cr<strong>an</strong>kshaft c<strong>an</strong> only <strong>be</strong> reground once <strong>to</strong> -.010"undersize, otherwise heat treatment is required, <strong>an</strong>d only rebored <strong>to</strong> +.020". Theflywheel now had six bolts <strong>to</strong> hold it on, as well as two dowels <strong>to</strong> locate it accurately,with a diaphragm spring clutch. As the reciprocating weights had increased with thebigger 1275cc pis<strong>to</strong>ns, the cr<strong>an</strong>kshaft nose was fitted with a heavy damper thatdoubled up as the f<strong>an</strong> <strong>be</strong>lt pulley. An improved cr<strong>an</strong>kcase vent system was introduced<strong>to</strong> replace the earlier problematicalinlet m<strong>an</strong>ifold valve. This simply vented in<strong>to</strong> the carburetter bodies via a smalldrilling by the throttle butterfly, from the timing chain cover oil trap. The system musthave the correct oil filler cap, as this controls the air entry, <strong>to</strong> run without it will give avery weak mixture. The 1275cc cylinderhead is longer, <strong>an</strong>d which exits its water at adifferent <strong>an</strong>gle <strong>to</strong> the 1098cc <strong>an</strong>d earlier heads, the three studs are differently placed.The 12CE units ( 12CD N.America,) have a bigger water pump with a larger inletdiameter pipe, requiring a bigger water hose.This 1275cc engine gave the Midget a much needed boost in power, but it did put itsperform<strong>an</strong>ce d<strong>an</strong>gerously near <strong>to</strong> that of the MGB, its bigger stablemate, with a 1798cc‘B’ series engine. Both cars power <strong>to</strong> weight ratio was similar, a bit more power <strong>to</strong> theMidget would me<strong>an</strong> it would embarrass the bigger car. The 1275cc ‘A’ series was fitted<strong>to</strong> the MG 1300, <strong>an</strong>d here gave 70bhp with 70 lb/ft <strong>to</strong>rque, whistling up <strong>to</strong> 60mph injust 14 seconds. The ADO16 was the reason for the 1275 engine, <strong>an</strong>d in it the saloon wasclose on the heals of the Midget, <strong>an</strong>d could <strong>be</strong>at the smaller engine versions of thesportscar. The Midget continued with its 12CC engine, until BMC ch<strong>an</strong>ged the system67

of num<strong>be</strong>ring, <strong>an</strong>d it <strong>be</strong>came the 12V, identical <strong>to</strong> the other, though painted black. All1275 engines had solid skirt pis<strong>to</strong>ns with gudgeon pins a press fit in<strong>to</strong> the connectingrods. Early 12G engines had four pis<strong>to</strong>n rings, later ones had three losing acompression ring. All Midgets with both the BMC ‘A’ series <strong>an</strong>d Triumph 1500 enginec<strong>an</strong> have hardend steel valve inserts fitted <strong>to</strong> the exhaust valve seats so they c<strong>an</strong> useleadfree fuel.The costs of trying <strong>to</strong> keep the North Americ<strong>an</strong> cars within the safety <strong>an</strong>d pollutioncontrols of that continent me<strong>an</strong>t the m<strong>an</strong>agement of BL had <strong>to</strong> chose <strong>be</strong>tween the ‘A’series Midget engine or the Triumph Spitfire 1500 unit. As Leyl<strong>an</strong>d ruled the day, theTriumph engine won, <strong>an</strong>d in Oc<strong>to</strong><strong>be</strong>r 1974 a M.G. had a ex-Triumph Herald enginefitted from the opposition, the Spitfire. The ‘A’ series was not <strong>be</strong>aten, it would rise likea phoenix from the ashes, in the M.G. Metro in 1982, but that is later.It is worth mentioning that the Morris Marina 1300 was produced from 1971, but its1275cc ‘A’ series 12V engine differs a lot from that of the Midget. Its cr<strong>an</strong>kshaft is cast asis the 1800 Marina’s, in a special production facility for this model. The term is ‘flowcast’<strong>an</strong>d is nearly as strong as the forged one of the M.G’s, but much cheaper. Itscylinder block is just as <strong>to</strong>ugh, but has the oil filter at the rear, over the starter mo<strong>to</strong>r,<strong>be</strong>hind the distribu<strong>to</strong>r, <strong>an</strong>d it uses the same throw away c<strong>an</strong>ister as the Metro’s. Thelater Marina 1300 has <strong>an</strong> 8" diaphragm clutch, the pre-1275cc Midget a 7 1/4" springclutch. To s<strong>to</strong>p the wrong flywheel <strong>be</strong>ing fitted, as the Marinas is much larger th<strong>an</strong> theMidgets, <strong>to</strong> fit its Triumph sourced, cast iron gearbox, the 1275cc Midget cr<strong>an</strong>k has twodowels, with a smaller diameter boss by about .020" . The Marina has one dowel, <strong>an</strong>dits boss is larger, so if you tried <strong>to</strong> fit a Midget flywheel, it will go over the one dowel,but will not pull up flush on<strong>to</strong> the boss; where as the Marina one c<strong>an</strong>not <strong>be</strong> put over thetwo dowels. Should you w<strong>an</strong>t <strong>to</strong> use a Marina block, especially the later ‘A’ Plus Italengine, you need <strong>to</strong> swap over the front plate, rear plate, <strong>an</strong>d a six bolt flywheel from a1275cc Midget, ( or drill a 1098cc one,) with the flywheel centre turned out a little <strong>to</strong>enable it <strong>to</strong> bolt up flush. The Marina side front mountings c<strong>an</strong> <strong>be</strong> thrown away, but doput the bolts back in the holes, some go through in<strong>to</strong> the cr<strong>an</strong>kcase, <strong>an</strong>d you will lose alot of oil otherwise.A St<strong>an</strong>dard Triumph <strong>Engine</strong>d M.G.M.G. Midget Mk3 1500 <strong>Engine</strong> 1974-79Oc<strong>to</strong><strong>be</strong>r 1974 saw the M.G. Midget roll out of Abingdon with a different engine, onecommonised with the Triumph Spitfire for the North Americ<strong>an</strong> market, the mainsportscar sales area. This engine has as long a his<strong>to</strong>ry as the ‘A’ series. It <strong>to</strong>o started lifeas a 803cc unit, for the St<strong>an</strong>dard 8hp of Septem<strong>be</strong>r 1953, <strong>an</strong>d the 10hp <strong>an</strong>d deluxePenn<strong>an</strong>t of May 1954. These were Austin A30 <strong>an</strong>d A35 competition, <strong>an</strong>d even hadsimilar styling, as well as very similar sized engines. The St<strong>an</strong>dard Eight was 803cc, (A30 size,) <strong>an</strong>d the St<strong>an</strong>dard Ten was 948cc,( A35 size.) The Eights engine was of greycast iron with pressed steel sump, timing cover, <strong>an</strong>d rocker cover, with a bore of 58mm<strong>an</strong>d a stroke of 76mm. If ever there was a copy, this was it, as the A30 engine has thesame dimensions, rather similar <strong>to</strong> William Morris copying the Ford 8hp side valveengine in 1935, that <strong>be</strong>came the USHM of the Morris Eight in 1936. It was not identical,as the ‘A’ series has its oil pump on the end of the camshaft, the St<strong>an</strong>dard engine has itsoil pump in the sump, driven off the same skew-gear as the distribu<strong>to</strong>r. With 7.25 <strong>to</strong> 1compression ratio the 803cc engine in the St<strong>an</strong>dard developed 26bhp at 4500rpm, with68

40 lb/ft <strong>to</strong>rque at 2800rpm. This power is fed through a 6 1/4" clutch. The Ten of 948ccwas the same stroke, but the bore was 63mm, ( A35?) It developed 35bhp at 4500rpm,<strong>an</strong>d 46 lb/ft <strong>to</strong>rque at 2500rpm, with a compression ratio of 7 <strong>to</strong> 1, <strong>an</strong>d could do 65mph;not bad for 1954.By April 1959 the models gave way <strong>to</strong> the St<strong>an</strong>dard-Triumph ‘Herald’ saloon, St<strong>an</strong>dard<strong>an</strong>d Truimph having merged, this using the 948cc engine of the Ten. The enginewas uprated <strong>to</strong> 8.5 <strong>to</strong> 1 compression ratio with twin SU carbs, producing a healthy45bhp at 5500rpm for the Herald Coupe for May 1959. This twin carb engine was boredout <strong>to</strong> 1147cc for the Herald 1200 <strong>an</strong>d a new sportscar, the Spitfire, based on the salooncomponents for 1962. The 1147cc had <strong>be</strong>en gained by offsetting the bores, siamesingthem, <strong>an</strong>d boring out <strong>to</strong> 69.3mm. With 9 <strong>to</strong> 1 compression, two SU HS2 carbs in theSpitfire mk1, it produced 63bhp at 5750rpm <strong>an</strong>d 67 lb/ft <strong>to</strong>rque. The Spitfire Mk2raised this <strong>to</strong> 67bhp in Decem<strong>be</strong>r 1964. By J<strong>an</strong>uary 1967 the Mk3 version of the Spitfirewith a 1296cc version of the engine was on sale. The bore was now 73.7mm with thesame 76mm stroke, <strong>an</strong>d 9 <strong>to</strong> 1 compression <strong>an</strong>d this uses two SU HS2 carbs. The powerrose <strong>to</strong> 75bhp at 6000rpm with 75 lb/ft <strong>to</strong>rque. A Mk4 version appeared in Novem<strong>be</strong>r1970, with the 1296cc engine, but it was cheapend with only 63bhp <strong>be</strong>ing produced at6000rpm, the reason for this was st<strong>an</strong>dardisation of the fleet’s engines. There was nowa 1296cc used in the Spitfire, Toledo, <strong>an</strong>d Dolomite 1300, <strong>an</strong>d a 1493cc engine, used inthe 1500, 1500TC, <strong>an</strong>d Dolomite 1500.The 1493cc had <strong>be</strong>en gained by lengthening the stroke, there was no more room <strong>to</strong>bore the cylinders <strong>an</strong>y wider, after all it was only a St<strong>an</strong>dard Eight/Ten/Penn<strong>an</strong>t blockof 1953. A longer throw cr<strong>an</strong>kshaft was also needed for this bigger engine, that onlyhad three main <strong>be</strong>arings. At 73.7mm bore <strong>an</strong>d 87.5mm stroke it had 9 <strong>to</strong> 1 compressionin the Spitfire 1500 of Decem<strong>be</strong>r 1974, introduced for the Americ<strong>an</strong> market with theM.G. Midget 1500 following in Oc<strong>to</strong><strong>be</strong>r of that year. British Leyl<strong>an</strong>d had grouped a lo<strong>to</strong>f competing British firms under one roof, <strong>an</strong>d were not disposed <strong>to</strong> the ailing ex-BMCcomp<strong>an</strong>ies. They had a large market in the USA for sports cars.In 1973 a de-<strong>to</strong>xed engine had <strong>be</strong>en produced for the USA market by Triumph, thishad put the mockers on the poor ‘A’ series, as it was fin<strong>an</strong>cially foolish <strong>to</strong> have twosimilar sized sports car in the same comp<strong>an</strong>y, with different engines for the samemarket. The 1493cc engine was identical in both models, but not perhaps the idealchoice, with hindsight. It was a case of the MPJM of 1936 again, a slow revving enginewith a long stroke. With a compression ratio of 9 <strong>to</strong> 1 ( 7.5 <strong>to</strong> 1 for the USA,) it produced66bhp at 5500rpm <strong>an</strong>d 82 lb/ft <strong>to</strong>rque at 3000rpm in the Mk3 Midget 1500, less th<strong>an</strong> theM.G. Metro 1300’s 72bhp. The cam timing was 18;58;58;18 <strong>an</strong>d the engine bolted <strong>to</strong> aMorris Marina gearbox with synchromesh on all four forward gears. It had full flowoil filtration, <strong>an</strong>d fully floating gudgeon pins like the 1098cc ‘A’ series. The cr<strong>an</strong>kshafthad main <strong>be</strong>aring sizes of 2.3" <strong>an</strong>d big ends of 1.875", both bigger th<strong>an</strong> the 1275cc ‘A’engine. This allowed regrinding up <strong>to</strong> -030" undersize. The 1500 performed wellenough, its capacity giving the light Midget some go. The 7 1/4" clutch was thediaphragm type <strong>an</strong>d very smooth. The version used for the USA had terrible powersapping items fitted, like air pumps, exhaust gas recirculation valves, <strong>an</strong>d so on.<strong>How</strong>ever, in the USA it did use the electronic Lucas 45/DE4 distribu<strong>to</strong>r.There is a tale that design m<strong>an</strong>agement at St<strong>an</strong>dard Triumph w<strong>an</strong>ted <strong>to</strong> move thebore centres out so the engine could <strong>be</strong> enlarged. The machine minder who had <strong>be</strong>enthere for donkeys years, said they could not <strong>be</strong> moved, the machine would not adjust.One night a technically minded m<strong>an</strong>ager s<strong>to</strong>le down from his office, <strong>an</strong>d saw theycould <strong>be</strong> moved, the machine <strong>be</strong>ing like all other boring machines, <strong>be</strong>ing adjustable byundoing a few locking bolts. The ‘jobsworth’ machine minder was amazed, he had69

The original 803cc St<strong>an</strong>dard Eight engine of 1953, that grew in<strong>to</strong> that fitted <strong>to</strong> the MG Midget 1500 in 1974.70

een telling m<strong>an</strong>y m<strong>an</strong>agers for m<strong>an</strong>y years it could not <strong>be</strong> done. Goes <strong>to</strong> prove the <strong>be</strong>stm<strong>an</strong>agers are those who c<strong>an</strong> do the job as well, not just businessmen/women.From personal memories of running a 1098cc Midget, a 1275cc Midget, <strong>an</strong>d a TriumphSpitfire, I seem <strong>to</strong> remem<strong>be</strong>r the Spitfire engine was difficult <strong>to</strong> keep oil tight.Both BMC <strong>an</strong>d Triumph engines leak oil, that I am afraid is part of their engineeringheritage, but the Triumph does have some odd joints in its block. I found the ventsystem hoses would clog up with solid carbon on the controlled breathing engines,causing cr<strong>an</strong>kcase compression, oil consumption <strong>an</strong>d oil leaks. The pipe need regularcle<strong>an</strong>ing out, or renewing, the cause <strong>be</strong>ing short journeys.The Midget faded away in Novem<strong>be</strong>r 1979.Oops!!On the ‘A’ <strong>an</strong>d ‘B’ series, the distribu<strong>to</strong>r is driven off a skew gear on the oppositeside of the engine, requiring a short ‘jack-shaft’. This locates in a hole one side, <strong>an</strong>ddrives the distribu<strong>to</strong>r using a ‘D’ drive, the other. To lift it out requires a 5/16" UNFstud, those of the rocker cover <strong>be</strong>ing ideal, as they will screw in<strong>to</strong> the threaded endprovided for this. People who do not know this get it out without trouble, but have<strong>be</strong>en known <strong>to</strong> drop it in<strong>to</strong> the sump when trying <strong>to</strong> refit it in the correct position.In the export 850cc Mini for Jap<strong>an</strong>, the ‘A’ series was made unleaded. This led <strong>to</strong>m<strong>an</strong>y miles of testing, 500 per day. After only 3 days on unleaded the Mini’scylinderhead was ruined by valve regression. Jap<strong>an</strong> has never used tetra-Ethyl-Lead,so all its vehicles have always <strong>be</strong>en ‘unleaded’.The ‘A’ Series in a M.G. SaloonM.G. 1100 <strong>Engine</strong>.(1962-67)Due <strong>to</strong> the success of the ADO15 Mini in 1959, it had <strong>be</strong>en followed by a similar butbigger car, the ADO16, known as the 1100/1300 front wheel drive r<strong>an</strong>ge. It was thismodel BMC had developed the 1098cc engine for. One of the six models was marketedas <strong>an</strong> M.G. in 1962, the MG 1100, as a two <strong>an</strong>d four door. The ‘A’ series under the bonnetwas pure Mini design, but bigger capacity. The cylinder block was not interch<strong>an</strong>geablewith the similar sized 1098cc MG Midget, as the rear main <strong>be</strong>aring was very different,<strong>an</strong>d the cr<strong>an</strong>kshaft had a longer tail for the reversed dry clutch with a gear <strong>be</strong>hind <strong>to</strong>drive the gearbox underneath via <strong>an</strong> idler-gear <strong>be</strong>tween. This idler-gear did get areputation for rapid wear, giving out a characteristic loud rattle if idle rpm was <strong>to</strong>oslow. The 1098cc MG 1100 still had the 1.75" main <strong>be</strong>arings of the early 10CG Midget.Otherwise it was very like the sportscar unit, with twin SU HS2 carburetters, on a 64.5bore by 84mm stroke, 8.9 <strong>to</strong> 1 compression, 10GR engine. The st<strong>an</strong>dard 1100 saloonhad 8.5 <strong>to</strong> 1 compression with 48bhp at 5100rpm, with 60 lbs <strong>to</strong>rque.For 1967 only theUSA MG 1100 had a single SU HS4.The cam timing was the same as the Midget 1098cc at 5.45.52;21 with .312" lift,producing 55bhp at 5800rpm <strong>an</strong>d 61 lb/ft <strong>to</strong>rque. At 5800rpm the engine certainly letthe driver know it was there. The 12G206 cylinder head used the larger 1.21" inletvalves of the Mini Cooper, <strong>an</strong>d the MG 1100 <strong>an</strong>d Riley Kestrel that shared the unit, hada free- flowing exhaust system. It did not use the mech<strong>an</strong>ical fuel pump, but <strong>an</strong> SUelectrical one. Oil consumption <strong>an</strong>d oil pump wear were a problem early on, but as in71

THE POWER UNIT AND TRANSMISSION(Twin-carburetter Version)72

the Mini, the pump was ch<strong>an</strong>ged from a rotating v<strong>an</strong>e type <strong>to</strong> a Holbourn-Ea<strong>to</strong>neccentric ro<strong>to</strong>r. The v<strong>an</strong>e one was not up <strong>to</strong> the bigger ‘A’ series. Oil control rings wereimproved by fitting Duraflex versions, these are three-piece items with two railsseparated by <strong>an</strong> exp<strong>an</strong>der, now common. Better quality control on pis<strong>to</strong>ns also helped,each bore <strong>be</strong>ing stamped with a code for its size, <strong>an</strong>d a matching pis<strong>to</strong>n fitted in sets.M.G. 1300 Mk1 <strong>Engine</strong> (1967-68) MG 1300 Mk2 (1968-71)The car sold well, but it <strong>to</strong>ok until 1967 for BMC <strong>to</strong> fit the 1275cc version of the ‘A’series for the UK, a 12G,( or later 12GR engine, commonising it with the Riley Kestrel.)The Americ<strong>an</strong> market was soaking up the 1275cc engined cars. The 1275cc 12GR enginegained the adv<strong>an</strong>tages of the 1300 group, in that the main <strong>be</strong>arings grew <strong>to</strong> the 2" of thelater 10CC Midget. Some early 12G engines had the 948/1098 big end size of 1.625", butas the steel quality of the cr<strong>an</strong>kshaft, soon <strong>to</strong> <strong>be</strong> used on the Marina 1300, was not sogood, so <strong>to</strong> retain the strength the big ends grew <strong>to</strong> 1.75" diameter. This Mk1, 12Gengine only had a single SU HS4 carburetter, producing 60bhp. The camshaft was stillthe 5;45;51;21 timed item. Valves head sizes were inlet 1.3" <strong>an</strong>d exhaust 1.15", as on the1275cc Midget. The Riley Kestrel <strong>an</strong>d V<strong>an</strong>den Plas 1300 shared the engine. The morepowerful post April 1968, MG 1300 Mk2, had 70bhp at 5250rpm with 70 lb/ft of<strong>to</strong>rque, once fitted with twin SU HS2 carburetters, now <strong>be</strong>ing a 12GR unit, with a 11stud head. This made it quite a nippy car, one that could keep on the heels of a 1275Midget for inst<strong>an</strong>ce, (0 <strong>to</strong> 60 in 14.5 seconds.) 95mph with 0 <strong>to</strong> 60 in 14 seconds wasexcellent then. This also embarrassed the MGB (13 seconds,) <strong>an</strong>d left the other saloon,the Mk4 Magnette ( 19.5s ) st<strong>an</strong>ding at the traffic lights.There was also <strong>an</strong> au<strong>to</strong>matic MG 1300, that used a single SU HS4 on the 1275ccengine, producing 58bhp, it was the same unit all the 1300 fwd au<strong>to</strong>matic cars hadfitted, <strong>an</strong>d very similar <strong>to</strong> the 12G engine. Not m<strong>an</strong>y sold, <strong>an</strong>d it died late 1968.Oil consumption was noticeable on the 1098cc at speed when worn a little, <strong>an</strong>d thiswas traced <strong>to</strong> the poor sealing of the inlet valve stem, easily diagnosed by lifting yourfoot right off the throttle on a long down hill run, letting the car drive the engine. Whenyou accelerate again at the bot<strong>to</strong>m, watch in the rear view mirror, lots of blue smokemay well <strong>be</strong> just worn inlet valve guides, <strong>an</strong>d/or valve stem seals. The old rub<strong>be</strong>r ringunder the collets did not s<strong>to</strong>p the inlet m<strong>an</strong>ifold sucking oil down the guide, fittedsince the 803cc. So it was ch<strong>an</strong>ged <strong>to</strong> <strong>an</strong> improved neoprene cap-seal that gripped thestem, <strong>an</strong>d sat over the <strong>to</strong>p of the inlet valve guide, <strong>an</strong>d was fitted on all the 998, 1098, &1275cc engines from then onwards. With a little tuning the MG 1300 would out h<strong>an</strong>dle<strong>an</strong>d <strong>be</strong>at the Midget. Both 1098cc <strong>an</strong>d 1275cc ADO16 engines c<strong>an</strong> <strong>be</strong> modified forleadfree fuel, buy fitting hardend steel exhaust valve seats. In 1971 the model wasdiscontinued after 143,067 cars, as Austin w<strong>an</strong>ted <strong>to</strong> sell their Austin 1300GT, that usedthe same engine.Identifying ‘A’ Series <strong>Engine</strong>s using ArchaeologyThe simplest way is <strong>to</strong> use the prefix <strong>to</strong> the engine’s num<strong>be</strong>r, stamped on a smalloblong plate riveted <strong>to</strong> the offside of the <strong>to</strong>p/front of the cylinder block, just above thedynamo. On both rwd <strong>an</strong>d fwd, if you have just a block, then it should have the cubiccapacity on a small tri<strong>an</strong>gular plate riveted near <strong>to</strong> the mech<strong>an</strong>ical fuel pump, or its73

l<strong>an</strong>king plate. This should say 850, 948, 1100, 1275, etc. If neither are there, you willhave <strong>to</strong> measure the bore <strong>an</strong>d stroke, <strong>an</strong>d even then check on main <strong>be</strong>aring sizes.A quick method <strong>to</strong> reduce the odds is <strong>to</strong> look at the oil filter. If it is <strong>an</strong> early roundc<strong>an</strong>ister screwed at right <strong>an</strong>gles <strong>to</strong> the block, under the dynamo, its <strong>an</strong> 803cc, rwd. If itis the paper/felt element type in a bowl facing down, with a pipe from the rear feeding<strong>to</strong> it, its a 949/1098/1275cc. If this bowl has a plate <strong>be</strong>tween it <strong>an</strong>d the block <strong>to</strong> raise it1", you have a Sprite/Midget block. A damper on the front of the cr<strong>an</strong>kshaft mayindicate a 1275cc. No side covers for the push rods is certainly a 1275cc. If the oil filteris above the starter mo<strong>to</strong>r, <strong>an</strong>d is a throw away c<strong>an</strong>, its a Marina/Ital 1275cc rwd block.Note that the Marina V<strong>an</strong> carried on with the old 1098cc engine.Early engines relied on two rub<strong>be</strong>r rings on the camshaft sprocket <strong>to</strong> tension thechain, which did not last very long, <strong>an</strong>d got a nickname of the ‘A’ series death rattlewhen worn. The 1275cc gained a decent chain tensioner, <strong>an</strong>d the bulge in the cover c<strong>an</strong><strong>be</strong> seen. A few extra holes drilled will allow earlier engines <strong>to</strong> retro-fit this, though theywill need <strong>to</strong> have the duplex chain & sprockets as well, <strong>an</strong>d two bolts on the front main<strong>be</strong>aring/front face of the front engine plate countersunk <strong>to</strong> miss the wider chain.Fwd engines are easy <strong>to</strong> recognise I hope. Again its the same with the enginenum<strong>be</strong>r <strong>an</strong>d the tri<strong>an</strong>gular plate, though all have the oil filter bowl, aluminium onearly Minis, steel later. Also the damper on the cr<strong>an</strong>kshaft, <strong>an</strong>d no push rod side coversme<strong>an</strong>s a 1275cc. A cr<strong>an</strong>kcase vent from the tappet chest will indicate a 1098cc engine,where as a vent from the timing chain cover a 1275cc. This is true on later rwd blocks aswell. The Metro/Montego has a throw away oil filter, as well as a differently formedengine num<strong>be</strong>r from the old BMC system. A bare block will have no scroll at the rearfor the rear main <strong>be</strong>aring. Second h<strong>an</strong>d engine num<strong>be</strong>rs are often chiselled off forunknown reasons!!The bit that causes problems is the cylinderhead, as these will fit <strong>an</strong>y engine, exceptthe Coopers with their two extra studs. The method had <strong>to</strong> <strong>be</strong> the casting num<strong>be</strong>r,under the rocker cover <strong>an</strong>d usually well drowned in oily black muck.Model Casting num<strong>be</strong>r Combustion cc inlet/exhaust size803cc & 848cc 2A 628,12A 1456,2A 629 24.5cc 1.06" 1"997cc & 1098cc 12G 202 26.1cc 1.15" 1"998, & 1098 MG 12G 206, 12G 295 28.3cc 1.21" 1"1275cc 12G 940 21.4cc 1.31" 1.15"1275 cc (MG1300& 1300GT) 12G 940 21.4cc 1.4" 1.15"All Cooper ‘S’ 12A 185, AFG 163 21.4cc 1.4 1.15"MG Metro Turbo 12G 940 21.4cc 1.31" 1.15"Note that casting num<strong>be</strong>rs were the same for different finished items, this num<strong>be</strong>r isthat of the wooden pattern only, the casting c<strong>an</strong> <strong>be</strong> machined for different uses after,ending up with a different part num<strong>be</strong>r in the spares book. 12G940 could <strong>be</strong> drilled for9 or 11 studs. The Cooper ‘S’ heads all had 11 studs.74

The later 1275cc ‘A’ series cr<strong>an</strong>kshaft, of three main <strong>be</strong>arings. Two dowels on the flywheel boss would indicatethis is a MG Midget version. The ‘A’ series was a very popular little workhouse, <strong>an</strong>d a vry tuneable. For your£1 you got far more bhp th<strong>an</strong> for the equivalent spent on the ‘B’ series. This eventually embarrassed the poorMGB whose engine was <strong>be</strong>ing built on worn out fac<strong>to</strong>ry machinery <strong>to</strong>wards the end. For inst<strong>an</strong>ce the MG Metro1300 turned out 72bhp from a single carb 1275cc, when the twincarb 1798cc MGB allegedly made 95bhp.75

After Abingdon, ‘A’ Series after 1981M.G. Metro 1300 <strong>Engine</strong>. (1982-90)Still on the ‘A’ series, well worthy of a mention, is the M.G. Metro <strong>an</strong>d its sister carthe Turbo. The M.G. Metro came just two years after the last MGB, in 1982. For thismodel BL <strong>to</strong>ok a hard look at the ‘A’ series, <strong>an</strong>d decided <strong>to</strong> give it further life. Theyspent a fortune on renewing worn out machinery, <strong>an</strong>d improving the engine. The MarinaItal gained as well, as both were fitted with the <strong>be</strong>tter ‘A Plus’ unit, 12V, 10H <strong>an</strong>d12H engines, with its <strong>be</strong>tter flowing ports <strong>an</strong>d m<strong>an</strong>ifolds. The Metro is very Mini indesign, but bigger, with cast iron head <strong>an</strong>d block, with <strong>an</strong> aluminium alloy sumpcontaining the gearbox. The M.G. Metro 1300 updated <strong>an</strong>d mildly tuned engineproducing 72bhp at 6000rpm, <strong>an</strong>d 73 lbs <strong>to</strong>rque, from the 1275cc, giving <strong>an</strong>y Midget avery rough <strong>an</strong>d embarrassing time indeed, <strong>an</strong>d most MGB’s. A 0 <strong>to</strong> 60mph in just 11seconds <strong>an</strong>d a <strong>to</strong>p speed of 101mph were just what was needed <strong>to</strong> keep the name of MGalive. This all from a single SU carb, but very much improved in gas-flow, <strong>an</strong>d with 10.3<strong>to</strong> 1 compression ratio. A normal Metro 998cc 10H engine had 9.6 or optional 8.3. Theexhaust was a cast iron three-in<strong>to</strong>-two-in<strong>to</strong>-one system, <strong>an</strong>d much <strong>be</strong>tter th<strong>an</strong> the usualrestrictive BMC earlier m<strong>an</strong>ifolds. The inlet m<strong>an</strong>ifold was a nicely shaped water heatedone, for a single large SU HIF 44, 1 1/2", complete with a huge paper element air filter.The 1275 ‘A Plus’ still used the 2" main <strong>be</strong>arings <strong>an</strong>d 1.75" big ends of the ‘A’ series1275. Camshaft timing had the wide overlap of the Cooper ‘S’ at 9;41;49;11 with .318"lift at the valve.From 1985 all Metro 1300’s had Ducellier electronic ignition. 142,405MG Metro 1300s were made.The MG Metro Turbo has <strong>an</strong> exhaust powered, Garratt T3 Turbo-charger, <strong>an</strong>d 9.4 <strong>to</strong>1 compression. A waste gate on the turbo, <strong>an</strong>d the st<strong>an</strong>dard Metro compression ratio,combine <strong>to</strong> eliminate most turbo lag, <strong>be</strong>ing solenoid operated, permitted power up <strong>to</strong>93bhp at 6150 rpm <strong>an</strong>d 85lb/ft <strong>to</strong>rque at just 2650 rpm, the most powerful production‘A’ series ever. It was designed in conjunction with Lotus Cars, Colin Chapm<strong>an</strong>’sempire. This gave the little car a <strong>to</strong>p speed of 113mph, the fastest MG saloon up <strong>to</strong> then.It had Ducellier electronic ignition, oil cooler, modified head, <strong>an</strong>d uprated nitridedcr<strong>an</strong>kshaft, double valve springs, stronger pis<strong>to</strong>ns, big end <strong>an</strong>d main <strong>be</strong>arings. Any ‘A’series that is tuned needs stronger main <strong>be</strong>aring caps, the Cooper Minis either usedsteel caps, or a steel strap, as the cast iron centre one was known <strong>to</strong> break. There wereproblems with a thinner head casting block face, of the first few Turbos, using the 12G940 head. It blew head gaskets, cured only by going back <strong>to</strong> the original metalthickness. The waterways had <strong>be</strong>en enlarged <strong>to</strong> improve cooling of the exhaust valveseat area. The clutch centre plate was solid, ( like a diesel,) no damping spring fitted,<strong>an</strong>d the engine mountings were stiffer.The Metro Sport in 1988 shared the MG Metro 1300 engine, <strong>an</strong>d the Metro Sport GTathe MG Metro Turbo engine, both at a lower price.The MG Metro 1300 <strong>be</strong>came leadfree in 1989, with <strong>an</strong> engine prefix of 12H/F01. By1990 the car had a Rover K series engine, so not m<strong>an</strong>y were made. The leaded ‘A’ seriesis prefixed 12H/D24. BL & Austin/Rover made 142,405 MG Metros <strong>be</strong>tween 1982 <strong>an</strong>d1990. BL actually made 1,600,000 ‘A’ series powered Metros, up <strong>to</strong> 1991. Thecylinderhead, m<strong>an</strong>ifolds <strong>an</strong>d carb are a good swap on<strong>to</strong> <strong>an</strong>y 1275cc car, <strong>an</strong>d thecamshaft is quite sporting, ex-Mini Cooper ‘S’ timing. Metros do suffer from oil leaks, aperennial problem of British <strong>Engine</strong>ering it seems. Over 50,000 miles the gear selection76

od in<strong>to</strong> the back of the gearbox, which is <strong>be</strong>low the sump oil level, may leak. It costs afew pence <strong>to</strong> cure DIY using a new seal. The seals on the timing chain case, <strong>an</strong>d bothdrive shafts will eventually leak, again reasonably easy <strong>to</strong> replace, especially the driveshaft ones compared <strong>to</strong> a Mini.M.G. Metro 6R4 <strong>Engine</strong> ( 1984-89)Very little of this special production of 200 cars was Metro, built by British Leyl<strong>an</strong>d<strong>an</strong>d Williams Racing. It was <strong>an</strong> out <strong>an</strong>d out rally car, the title me<strong>an</strong>ing V6 cylinder-Rally-4 Wheel Drive. In 1984 a Rover V8 was cut down <strong>to</strong> a 2.5 litre V6, as the V8 wasjust <strong>to</strong>o big <strong>to</strong> fit. This was a twelve valve engine with six carburetters producing250bhp. In 1985 it was redesigned in<strong>to</strong> the V64V, ( V6, 4 Valves,) <strong>an</strong> all aluminium V6engine with <strong>be</strong>lt driven dohc per head, four valves per cylinder, at 3 litres capacity.With Lucas Micos fuel injection adapted from the Jaguar XJR-6 V12 racing car,electronic ingnition, tuned intake <strong>be</strong>ll-mouths <strong>an</strong>d exhaust system, it produced250bhp initially, <strong>an</strong>d was fitted amid-ships, with a five speed gearbox driving all fourwheels. It eventually produce 400bhp, but was detuned for reliability for Au<strong>to</strong>cross, <strong>to</strong>just 250hp. The fuel metering <strong>an</strong>d ignition timing was carried out by <strong>an</strong> Intel 8032Microprocessor. The spark was produced by a Lucas AB14-type ignition amplifierusing two Lucas 35C6 coils. In 1987 some were bored out <strong>to</strong> 3.8 litres, <strong>an</strong>d tuned <strong>to</strong>550bhp, normally aspirated, ( no help with the inlet stroke.) Some were also reduced <strong>to</strong>2.3 litres <strong>an</strong>d fitted with two exhaust powered turbo-chargers <strong>an</strong>d flew about with750bhp on tap, getting from zero <strong>to</strong> 60mph in just 3 seconds.Approximately 233 carswere produced.‘A’ Series Camshafts in M.G.sThere are m<strong>an</strong>y after market tuning kits <strong>an</strong>d camshafts for the ‘A’ series. This liststhose camshafts fitted <strong>to</strong> production cars only. The 1500 Midget is included. Earlycamshafts had 3/8" wide lo<strong>be</strong>s, later versions have 1/2" lo<strong>be</strong>s. Beware of comparingcam timing <strong>be</strong>tween different engine types, things like valve sizes, port shapes, carsuse, all affect perform<strong>an</strong>ce.Model Cam Timings Lift Part Num<strong>be</strong>r (if known)948cc Midget 5;45;45;5 .312" 12G 165, AEA 630,12G726.1098cc Midget 5;45;51;21 .312" AEG577, AEG323,AEG538.1275cc Midget 5;45;51;21 .318" AEG577, AEG323,AEG538.1493cc Midget 18;58;58;18M.G. 1100 5;45;51;21 .312" 12G 165, AEA 630,12G726M.G. 1300 5;45;51;21 .318" AEG577, AEG323,AEG538.M.G. Metro 1300 16;56;59;29 .318" AEG567, AEG568,( Mini Cooper cam) 88G229, 2A948, 12A 122M.G. Metro Turbo 9;41;49;11 .318"77

BMC ‘A’ SERIESA 1300 MG Metro has its cylinder head swapped for a lead-free converted one.78

BMC ‘A’ SeriesSt<strong>an</strong>dard 1300 MG Metro engine.MG Metro 6R4, ‘V64V’ engine. A somewhat faster Metro!79

The large <strong>be</strong>arings of the ‘A’ <strong>an</strong>d ‘B’ series camshafts often leads <strong>to</strong> them notrequiring renewal on reconditioned engines. A look at <strong>an</strong> Austin 8hp camshaft of 1935,that the ‘A’ camshaft is a clone of, shows it with huge <strong>be</strong>arings, where as the Morris ‘X’series has smaller ones. The XPAG’s camshaft looks like a bit of <strong>be</strong>nt wire incomparison.A twin camshaft cylinderhead was built for the ‘A’ series, in the early 60’s, now ondisplay at Gaydon Mo<strong>to</strong>r Museum. It was driven by a <strong>to</strong>othed <strong>be</strong>lt, <strong>an</strong>d designed byEric Bareham. It never reached production, but would have made a tidy Midget. Itproduced 80bhp at 6750rpm, <strong>an</strong>d was based on the Mini Cooper 998cc & 1275ccengines. It was never used, but it did lead <strong>to</strong> the ‘A’ Plus engine. A twin ohc kit for the‘A’ series is available by Jack Knight & KAD, from the larger Mini specialists thesedays, <strong>to</strong>othed <strong>be</strong>lt driven, should you w<strong>an</strong>t one.80

The original 1200cc Austin A40 engine of 1947, the one that led <strong>to</strong> the design of the‘B’ series in 1952. Yes it is very similar, but smaller all round, even bore centres arecloser <strong>to</strong>gether. Note the expendable by-pass oil filter, <strong>an</strong>d that it is NOT a’B’ series.The off side of the power unit showing: 1. Air cle<strong>an</strong>er clamp bolt. 2. Oil filler clap.3. Valve rocker cover cap nut. 4. haeter control valve. 5. Vacuum timing control.6. Welch plug. 7. Oil gauge union. 8. Cylinder drain tap. 9. Distribu<strong>to</strong>r clamp bolt.10. Starter pinion <strong>an</strong>d sleeve. 11. Dip-stick. 12. Starter mo<strong>to</strong>r switch 13. Drain plugfor sump. 14. External filter bolts. 15. Dynamo adjusting bolts. 16. Cylinder head nuts.81

British Mo<strong>to</strong>r Corporations ‘B’ sries engine, shown here in its 1498cc size of 1956, about<strong>to</strong> <strong>be</strong> fitted <strong>to</strong> the Wolseley 1500. It has <strong>an</strong> early type of vacuum adv<strong>an</strong>cecontrol on the distribu<strong>to</strong>r. Big ends aresplit diagonally so they could <strong>be</strong> withdrawn up trough the bores.Copyright is Au<strong>to</strong>car magazine April 1957.82

Wolseley 15/50 Saloon, 1957 Model(Supplement <strong>to</strong> “Mo<strong>to</strong>r Trader”, 30 Oc<strong>to</strong><strong>be</strong>r, 1957)The first 1498cc’B’ series <strong>an</strong>d its forward facing sump, with by-pass oil filter (no pipe).83

Chapter SixBMC ‘B’ Series M.G. <strong>Engine</strong>s1953 <strong>to</strong> 1980Potted His<strong>to</strong>ryA New <strong>Engine</strong> for M.G.The BMC Austin designed 1489cc ‘B’ series engine was first seen in <strong>an</strong> M.G. inOc<strong>to</strong><strong>be</strong>r 1953. It was shown at the 1953 Mo<strong>to</strong>r Show, <strong>an</strong>d caused a bit of a rumpusamong some who called themselves enthusiasts. The model was the air-smooth M.G.‘Z’ Magnette saloon car. It replaced the ‘Y’ type with its 1250cc XPAG engine, <strong>an</strong> enginethe comp<strong>an</strong>y’s Wolseley 4/44 would still <strong>be</strong> using three years later, till 1956.The source of the ‘B’ series goes a lot further back in mo<strong>to</strong>ring his<strong>to</strong>ry, as does itslittle sister the ‘A’ series, both <strong>be</strong>ing born from a 1200cc ohv Austin engine of 1947. This1200cc unit was one of a pair that Bill Appleby, Eric Bareham, <strong>an</strong>d Jimmy Rix, at theADO ( Austin Design Office,) is supposed <strong>to</strong> have crib<strong>be</strong>d from a lorry engine. Theoriginal unit was infact a ohv six cylinder Chevrolet engine that Vauxhall werebuilding <strong>to</strong> fit in their pre-war Bedford lorry. It was very successful, <strong>an</strong>d Austin gothold of <strong>an</strong> example, <strong>an</strong>d made his own slightly altered version. It was also verysuccessful so the <strong>Engine</strong> Design Department cloned it in<strong>to</strong> two smaller four cylinderversions, for use in the cars. One was a 2199cc 16hp engine, used in the post-war 1945Austin Sixteen saloon, 25cwt v<strong>an</strong>,<strong>an</strong>d early A90 Atl<strong>an</strong>tic, <strong>an</strong>d bored out <strong>to</strong> 2660cc in thelater A90 Atl<strong>an</strong>tic, Austin Taxi, the Champ, <strong>an</strong>d Austin Healey 100 sports car. The otherwas a very tidy unit of 1200cc, not unlike the ‘B’ series, but with a gear type oil pump<strong>an</strong>d by-pass oil filter, using the cr<strong>an</strong>kshaft, connecting rods, pis<strong>to</strong>ns, camshaft, <strong>an</strong>dbore centres from the pre-war Austin 10/4 of 1932, of 65.5mm bore <strong>an</strong>d 89mm stroke. Itproduced 40bhp at 4300rpm, with its Zenith carburetter. A good example of tying adesigner down <strong>to</strong> a price. It is NOT <strong>an</strong> ohv conversion of the Austin 10hp sidevalveengine, it was done so the same boring machine could <strong>be</strong> used <strong>to</strong> make the ‘new’engine. It was fitted <strong>to</strong> the four door A40 Devon <strong>an</strong>d two door Dorset models, in 1947,the same year the M.G. ‘Y’ type saloon was introduced.In 1953 it was redesigned in<strong>to</strong> the 1200cc <strong>an</strong>d 1489cc ‘B’ series by Eric Bareham <strong>an</strong>dJimmy Rix, <strong>an</strong>d this engine went in<strong>to</strong> the A40 Somerset in 1954, ( same A40, new body.)The 1947-1953 Austin 1200cc engine is not a ‘B’ series, though it looks similar. The newredesigned engine was of conservative design, in grey cast iron, with a pressed steelsump, timing chain cover, <strong>an</strong>d rocker cover. Its mech<strong>an</strong>ical petrol pump was driven offa lo<strong>be</strong> on the camshaft, <strong>an</strong>d it was a push-rod ohv unit with heart shaped ‘bathcham<strong>be</strong>r’ combustion cham<strong>be</strong>rs, developed by the same consult<strong>an</strong>t Harry Weslakewho had a h<strong>an</strong>d in the ‘A’ series. The cylinders were further apart th<strong>an</strong> the original A401200cc engine, <strong>an</strong>d the cr<strong>an</strong>kshaft was of EN16 carbon steel. The 89mm stroke me<strong>an</strong>tthe counterweights of the cr<strong>an</strong>k actually went within one sixthteenth of <strong>an</strong> inch of thecamshaft, something that limited <strong>an</strong>y lengthening of the stroke in later life. It was onlydesigned for a five year life after all. All ‘A’ <strong>an</strong>d ‘B’ series engines had theircompression ratios altered, within that engine’s model r<strong>an</strong>ge, by the differing dish inthe pis<strong>to</strong>n. This made production easier as only one cylinder head was required, <strong>an</strong>dshould you have <strong>an</strong> engine with a flat pis<strong>to</strong>n, this would <strong>be</strong> a high compressionversion. The cylinderhead had five ports, all four inlets were siamesed in<strong>to</strong> two, <strong>an</strong>d84

the two centre exhaust shared a port, just as in the MPJG Midget engine of 1936. Thiscentral exhaust port would me<strong>an</strong> the exhaust valves would run very hot, so only the<strong>be</strong>st steel was used in them. Even so, m<strong>an</strong>y larger ‘B’ series developed a name forrunning on after switching the ignition off, easily cured <strong>to</strong>day by fitting <strong>an</strong> <strong>an</strong>ti-run-onvalve from a Metro, <strong>to</strong> the inlet m<strong>an</strong>ifold. The camshaft design ensured the cam lasteda lot longer th<strong>an</strong> the XPAG versions. The camshaft was slightly offset from thecentreline of the followers above, so as the cam lo<strong>be</strong> rotated <strong>an</strong>d lifted the follower;<strong>be</strong>ing offset, it rotated the follower as well inside its bore. This reduced wear of bothparts considerably, as not just one area <strong>to</strong>ok all the stress, <strong>an</strong>d s<strong>to</strong>pped pocketing of thefollower’s lower face.Like the ‘A’ series, it was all the electric’s on one side of the block, <strong>an</strong>d fuel the other,for safety. The ‘B’ series had a paper/felt element oil filter in a bolt on steel bowl, but itwas still only a by-pass version, taking 10 miles <strong>to</strong> filter all the oil just once. Earlyengines have no oil pipe <strong>to</strong> this filter, which assists identification. The oil pump was <strong>an</strong>eccentric three lo<strong>be</strong> type, by Holbourne-Ea<strong>to</strong>n, driven from a skew gear off thecamshaft, with the distribu<strong>to</strong>r drive coming off the same gear via a jack-shaft that sits<strong>be</strong>tween the cylinders. This me<strong>an</strong>s the distribu<strong>to</strong>r is at <strong>an</strong> <strong>an</strong>gle on the other side.Connecting rods (con-rods ) had the pinch-bolt gudgeon pin <strong>an</strong>d diagonally split bigends so they could <strong>be</strong> withdrawn up via the cylinder. On old long-stroke sv engines itwas common <strong>to</strong> drop the sump, undo the big ends, <strong>an</strong>d wriggle the pis<strong>to</strong>n down pastthe cr<strong>an</strong>kshaft; ohv engines usually have pis<strong>to</strong>ns that are <strong>to</strong>o big for this havingbroader bores. The 89mm stroke was <strong>to</strong> give the engine good mid r<strong>an</strong>ge <strong>to</strong>rque, butwould limit rpm, <strong>an</strong>d development; not that the designer had <strong>an</strong>y idea his enginewould still <strong>be</strong> about in 1980’s. It had three main <strong>be</strong>arings on its counterbal<strong>an</strong>cedcr<strong>an</strong>kshaft that were a larger diameter th<strong>an</strong> the A40 1200 unit of 1947. The timing chainhad a tensioner, which the earlier engines <strong>be</strong>fore 1954 did not.The 1200cc version onlylasted until 1957, but the 1489cc ‘1500’ was still in use in the Wolseley 1500 as late as1965. Of all engines in this book the ‘B’ is the easiest <strong>to</strong> identify, as they have theircapacity cast in num<strong>be</strong>rs on the nearside front of the block, under the dynamo, ‘1200’for 1200cc, <strong>an</strong>d ‘1500’ for 1489cc, for these early units; <strong>an</strong>d ‘1600’ for 1588cc, ‘1622’ for1622cc, <strong>an</strong>d ‘1800’ for 1798cc. It is one of the heaviest engines about for its size, 370lbsfor a 1489cc, less gearbox; 520lbs for a 1798cc with gearbox. ( Make sure that garageroof is strong enough.)As Austin <strong>an</strong>d Morris had amalgamated, both had huge engineering capacity, <strong>an</strong>d the‘A’ <strong>an</strong>d ‘B’ were build by Morris <strong>Engine</strong>s <strong>an</strong>d at Longbridge, now the BMC <strong>Engine</strong>sDivision. Austin also used good quality metals in his cars <strong>an</strong>d mech<strong>an</strong>ics, both firmshad excellent reputations for good service <strong>an</strong>d long life of their engines. Austin’s forinst<strong>an</strong>ce could go for 100,000 miles whilst current Fords of the time were often wornout at 35,000. The ‘B’ series was just that, a hard working, long lasting unit, a name that<strong>be</strong>came a by-word for reliability, if not high power. The ‘B’ does leak oil, especiallyearly units that have the felt front timing cover seal, <strong>an</strong>d the rear reverse-scroll seal.Slight cr<strong>an</strong>kcase compression, <strong>an</strong>d a bit of wear, will allow this rear seal <strong>to</strong> weep, <strong>an</strong>dleave you a little signature on the cle<strong>an</strong> drive via the <strong>be</strong>ll housing drain hole. Laterengines had a modern front seal, but it was not until the 1800 five main <strong>be</strong>aring enginedid we get a decent neoprene sprung rear seal. M.G. were once again <strong>to</strong> take a bread<strong>an</strong>d butter engine, <strong>an</strong>d use it <strong>to</strong> adv<strong>an</strong>tage in their sports car <strong>an</strong>d saloons.To launch the new BMC 1500 engine, <strong>an</strong>d <strong>to</strong> cement the merger with Morris theprevious year, the new M.G. ‘Z’ Magnette was <strong>to</strong> have this Austin power unit. It was <strong>to</strong><strong>be</strong> used in m<strong>an</strong>y of the BMC, BL, Austin/Rover cars over the years. M.G. were used a85

THE ENGINEEnd view of a 1489cc ‘B’ series with later sw<strong>an</strong>- neck breather pipe.86

THE ENGINESide view of 1489cc ‘B’ series, with very early evacuated-<strong>be</strong>lows type the rthermostat.87

lot by BMC <strong>to</strong> do product testing, as their cus<strong>to</strong>mers were a lot harder on the items suchas engines th<strong>an</strong> the family m<strong>an</strong>/wom<strong>an</strong>. Quite a num<strong>be</strong>r of improvements were madeover the years <strong>to</strong> the ‘B’ series, the fault first seen in <strong>an</strong> M.G. ‘A’ or ‘B’ series. Perhaps itwas thought <strong>an</strong> enthusiast was more likely <strong>to</strong> put up with such things. A list follows,the first part uses the old Morris num<strong>be</strong>ring system, ( see earlier expl<strong>an</strong>ation underXPAG,) the rest use the BMC code as shown under the ‘A’ series.Note that engine num<strong>be</strong>rs on second-h<strong>an</strong>d units are often chiselled off, <strong>to</strong> hide itsorigin perhaps!Model cc Prefix BHP/RPM TorqueAustin A40 Devon 1200 BP12A 40/4300 58 lb/ftAustin A40 Somerset 1200 BP12A 42/4500 58Austin A40 Sports 1200 BP12A 42/4500 58Austin A40 Sports 1200 BP12A 46/4500 58Morris Cowley Series 1 1200 BP12M 40/4500 58Austin/Nash Metropol. 1200 1200 BP12A 40/4500 58Austin/Nash Metropol. 1500 1489 BP15A 52/4500 70Morris Oxford Series 2 1489 BP15MH 50/4500 70Morris Oxford Ser 2 (low comp) 1489 BP15ML 45/4500 65Morris Cowley Series 2 1489 BP15M 50/4500 70Morris Oxford Series 3 1489 15M 55/4500 72Morris Oxford Series 4 1489 15M 55/4500 72Wolseley 15/50 1489 BP15W 50/4500 70Wolseley 15/50 1489 15AMW 55/4500 72Wolseley 1500 Mk1 1489 BP15LAW 50/4500 70Wolseley 1500 Mk2 1489 15W, 15WA 55/4500 72Riley 1.5 Mk1 1489 15R, 15RA 60/4800 77Riley 1.5 Mk2 1489 15RB 66/5200 82M.G. Magnette ZA* 1489 BP15GA 60/4600 77M.G. Magnette ZB 1489 BP15GC 68/5200 82M.G. MGA 1489 BP15GB 68/5200 82M.G. MGA 1489 BP15GD 72/6000 85M.G. MGA Twin Cam 1588 BC16GB 108/6700 104M.G. MGA 1600 1588 16GA 80/5600 87J Type 1 / 2<strong>to</strong>n Commercial V<strong>an</strong> 1489 BP15ML, 15AC 50/4200 74Diesel <strong>Engine</strong> 1489 BP15J,15Y,15Z 40/4200 90Austin A50 Cambridge 1489 1H 50/4500 70Austin A55 Cambridge 1489 15 55/4500 72Austin A55 Cambridge Mk2( Farina) 1489 15AMW 55/4500 82Morris Oxford Series 5 (Farina) 1489 15AMW 55/4500 82Wolseley 15/60 ,, 1489 15AMW 55/4500 82Riley 4/68 ,, 1489 15RA, 15RB 68/5200 85M.G. Magnette Mk3 ,, 1489 15GE 66/5200 85Morris Oxford Series 6 ,, 1622 16AMW, 16AA 61/4500 90Di Tella, (Argentina) ,, 1489 15AMW 55/4500 82Austin Cambridge A60 ,, 1622 16AMW,16AA 61/4500 90Wolseley 16/60 ,, 1622 16AMW, 16AA 61/4500 90M.G. Magnette Mk4 ,, 1622 16GE, 16GF 68/5200 89Riley 4/72 ,, 1622 16RA, 16GF 72/5500 9088

M.G. MGA 1600 Mk2 1622 16GC 92/5500 97A60 1/2 <strong>to</strong>n Commercials 1622 16AC, 16AE 61/4500 90Farinas with Alterna<strong>to</strong>rs,(’71 only) 1622 16C 61/4500 90BMC 1/2 Ton V<strong>an</strong> 1622 16AD 61/4500 90BMC ‘B’ Gold Seal recon-engines All 48GSherpa V<strong>an</strong>, low compression, 1622 16V 58/4500 82Sherpa V<strong>an</strong> ,, 1798 18V 80/5000 85Morris Marina 1800 1798 18V 85/5000 90Morris Marina 1800 TC 1798 18V 95/5400 *** 110Austin 1800 Mk1 1798 18C, 18AMW 80/5000 90Morris 1800 Mk1 1798 18C,18AMW 80/5000 90Wolseley 18/85 1798 18C,18AMW 80/5000 90All fwd 1800 Mk2 1798 18C, 18WB 86/5300 92All fwd 1800 Mk3 1798 18H 86/5300 95Austin 1800’S’ 1798 18H 96/5400 106MG. MGB three main <strong>be</strong>arings, 1798 18G, 18GA 95/5400 110M.G. MGB five main <strong>be</strong>aring, 1798 18GB,18GD,18GG, 18GH18GF, 18GJ,18GK, 18GJ18GC & 18V 95/5400 ** 110Hindust<strong>an</strong>i 1500 1489 ? 50/4200 74Naviga<strong>to</strong>r Marine 1489 ? 42/4200 60Naviga<strong>to</strong>r Marine 1622 ? 58/4500 85* Our first model with the ‘B’ series, <strong>an</strong>d ** the MGB had lost power down <strong>to</strong> the low70’s for the USA market by 1980, <strong>an</strong>d look under ‘MGB’ for its extra engine prefixes.***this is a MGB engine, but see under ‘MGB’. The vehicles using the same engine c<strong>an</strong>quickly <strong>be</strong> spotted by this list, <strong>an</strong>d the ‘H’ <strong>an</strong>d ‘V’ me<strong>an</strong> the same as in the ‘A’ series forfwd <strong>an</strong>d rwd.By 1956 BMC had made 250,000 ‘B’ series engines, <strong>an</strong>d by 1960 over 2,000,000 had<strong>be</strong>en made. By the end <strong>an</strong> estimated 3,500,000 ‘B’ series had <strong>be</strong>en produced, notincluding those 1498cc versions still currently <strong>be</strong>ing made by Hindust<strong>an</strong>i in India, fortheir h<strong>an</strong>d built version of the 1956-59, BMC Morris Cowley 1500.Like the earlier XPAG Morris based engine, this Austin based ‘B’ series is quite <strong>an</strong>audible engine, it does suffer tappet clatter even with its .015" clear<strong>an</strong>ces. Today’s moderncar driver who buys such <strong>an</strong> engined classic should remem<strong>be</strong>r this, <strong>an</strong>d accept itis not as refined, or as full of sound deadening, as his/her modern everyday car. Apartfrom noise, the other trade mark of the ‘B’ is its well hidden oil filter on m<strong>an</strong>y models,difficult <strong>to</strong> get <strong>to</strong> above the suspension cross mem<strong>be</strong>r. On the later 1800’s it ch<strong>an</strong>ged <strong>to</strong>a upward facing position, but not for the convenience of you or I, but <strong>to</strong> clear steeringcolumns!There is a lot of the ‘B’ series in early Niss<strong>an</strong>-Datsun cars, as they assembled CKDexport Austin 1200cc A40 Devons <strong>an</strong>d 1489cc A50 Cambridges in the early 1950’s. Laterthey <strong>to</strong>o crib<strong>be</strong>d the ‘B’ series design, fitting it in<strong>to</strong> m<strong>an</strong>y of their models, but it was a‘mirror’ image, everything on opposite sides.89

Known Modifications During ProductionBecause of the massive num<strong>be</strong>r of vehicles the B series engine was fitted <strong>to</strong>, oversuch a long period, only <strong>an</strong> overview is given. Use your own car’s m<strong>an</strong>ual for accurateinformation.Date Model Modification. .Oc<strong>to</strong><strong>be</strong>r 1953 M.G. ZA Magnette New 1489cc ‘B’ series engine.J<strong>an</strong>uary 1954 All Reynolds timing chain tensionerfitted.Oc<strong>to</strong><strong>be</strong>r 1954 Austin A40 <strong>an</strong>d A50 Gain the 1200 & 1489cc engines.Oc<strong>to</strong><strong>be</strong>r 1954 Oxford s2 & Cowley S2 Gain the 1200 & 1489cc engines1955 All Oil pump output increased.1956 All Full flow oil filter fitted.1956 Austin & Morris 1200 discontinued, but it did carryon in Eire in the A50 till 1959.1958 All Vent pipe from cr<strong>an</strong>kcase given asw<strong>an</strong>-neck <strong>to</strong> s<strong>to</strong>p oil loss.1958 M.G. MGA 1489 bored out <strong>to</strong> 1588cc for usein MGA Twin Cam & MGA 1600.Novem<strong>be</strong>r 1958 All Exhaust m<strong>an</strong>ifold improved, <strong>an</strong>dAustins lose their Zenith carbs forS.U. increasing power by 2bhp.1959 BMC Australia Try out the 1622cc engine.1960 Austin & Morris 1489cc Diesel version.Septem<strong>be</strong>r 1961 Farina models & MGA 1622cc introduced in UK, biggervalves, stronger engine.June 1962 MGB 1800 1798cc three main <strong>be</strong>aring, 18G<strong>an</strong>d 18GA fitted <strong>to</strong> new MGB.February 1964 MGB-export Closed circuit breather system.Oc<strong>to</strong><strong>be</strong>r 1964 FWD Austin 1800 1798cc engine used in fwdtr<strong>an</strong>sverse location. Five main<strong>be</strong>arings on cr<strong>an</strong>kshaft.Oc<strong>to</strong><strong>be</strong>r 1964 MGB Five main <strong>be</strong>aring engine, 18GB,Rear oil seal on cr<strong>an</strong>kshaft, <strong>an</strong>dfully floating gudgeon pins.1965 Riley 1.5 & Wolseley 1500 Last 1489 in saloon car, but itcarried on in the v<strong>an</strong>s until 1959.Novem<strong>be</strong>r 1966 Farina & MGB Bits of 1622 <strong>an</strong>d 1798cc enginescommonised, water pump, sump,<strong>an</strong>d larger capacity oil pump.Now 16AA <strong>an</strong>d 16GF.1968 1800 ‘S’ Biggest inlet valve head fitted,1.625" dia, 12H2708.Smaller combustion cham<strong>be</strong>r,most powerful st<strong>an</strong>dard ‘B’August 1970 MGB North America Emission Control fitted.August 1970 MGB &Austin/Morris 1800 Closed circuit breather now fedin<strong>to</strong> carb body, for UK market.1971 MGB & Marina 1800 <strong>Engine</strong>s commonised, now 18V.April 1971 Farina & MGB Last 1622 engine.90

1975 MGB Gains a catalytic converter forUSA market.1978 Marina 1800 Last Morris car with a ‘B’.1978 Princess s2 First use of ‘O’ series.Oc<strong>to</strong><strong>be</strong>r 1980 MGB Last MGB.1980 Sherpa Last ‘B’ series.‘B’ Series Camshafts in M.G. <strong>Engine</strong>s.Model Cam Timing Lift Part Num<strong>be</strong>r Inlet & Exhaust ValvesZA Magnette <strong>to</strong> 18101 5;45;40;10 .312" 48G184 1.375" 1.28"ZA & ZB Magnette 5;45;40;10 .312" 48G184 1.5" 1.28"All MGA 16;56;51;21 .355" 88G252 1.5" 1.28"MGA Twin Cam 20;50;50;20 ? 1.6" 1.44"Mk 3 Magnette <strong>to</strong> 8067 5;45;40;10 .312" 48G184 1.5" 1.28"Mk3 & Mk4 Magnette tdc;50;35;15 .312" 12H76 1.5" 1.28"MGB, MGB GT 16;56;51;21 .355" 88G303 1.56" 1.34"MGB’s after Oct ’67 16;56;51;21 .355" 12H2746 1.625" 1.34"The lift on the chart is at the valve, as the rockers act at a ratio of 1.4, the actual lift onthe cam lo<strong>be</strong> is .220" for a .312" lift, <strong>an</strong>d .250" for a .355" lift. The part num<strong>be</strong>rs of BMCch<strong>an</strong>ge at lot for the same item, depending upon the supplier, hence a 12H76 is also a12H34. A 48G184 is also a 1H603,1G2591,1H1066. <strong>an</strong>d a 88G252 c<strong>an</strong> <strong>be</strong> a88G303,12H2746,1H1435,1H729,12H1647 <strong>an</strong>d 12H1656. Clear now?The ‘big’ inlet valve head of the post ’67 MGB is the one commonised with theAustin 1800 ‘S’. Cylinder heads are like those of the ‘A’ series, <strong>an</strong>y ‘B’ head will fit <strong>an</strong>y‘B’ series engine, from 1200cc in 1953 <strong>to</strong> 1798cc in 1980. This sounds good until you notethe valve <strong>an</strong>d combustion cham<strong>be</strong>r sizes, some swaps produce vintage compressionratios, other cause the inlet valve <strong>to</strong> hit the block with serious results. An easy checkpoint of a 1798cc cylinder block with the head off, is the small scalloped out radii in theside of the bore, there <strong>to</strong> give clear<strong>an</strong>ce <strong>to</strong> that inlet valve. This scallop is required iffitting a 1800 head <strong>to</strong> <strong>an</strong>y other engine. A 1800 cylinderhead has the num<strong>be</strong>r “18” castat the rear end, <strong>be</strong>hind the rocker cover <strong>to</strong> assist you identify it, <strong>an</strong>d like the 1275cchead, it is slightly longer th<strong>an</strong> the smaller engines.‘B’ Cylinderheads.Only a general picture is given here, using the combustion cham<strong>be</strong>r capacity.<strong>Engine</strong> Size, Cham<strong>be</strong>r cc, Comp-ratio, Part No (if known.)1200cc saloons 38cc 8.3 or 7.2 ?1489cc saloons 39cc 8.3 or 7.2 48G2411489cc commercials 39cc 7.2 48G2411489cc M.G./Riley 39cc 9.0 or 8.3 or 7.2 12H16701622cc saloons 43cc 8.3 or 7.2 12H16701622cc M.G. /Riley 43cc 8.9 or 8.3 12H167091

Second h<strong>an</strong>d bargains?A 18V MGB engine. Why has it got a 1.8 Morris Marina plastic f<strong>an</strong>?Later disposable c<strong>an</strong>nister oil filter facing upwards, <strong>to</strong> miss the steering column.92

1622cc commercials 43cc 8.3 or 7.2 12H16701798cc MGB 43cc 9.0 or 8.1 12H13261798cc M.G./Marina 43.5cc 9.0 or 8.1 12H2706,12H27091798cc commercials 43.5cc 9.0 or 6.9 12H27091798cc 18V & 18H 43.5cc 9.0 or 8.0 12H4735 offset oil feed.1798cc 1800 ‘S’ 37cc 9.5* 12H2708* Bigger 1.625" diameter inlet valve. The last shown, on the Austin 1800’S’, with itssmaller 37cc combustion cham<strong>be</strong>r is very hard <strong>to</strong> source. Part num<strong>be</strong>r is cast in<strong>to</strong> thehead, under the rocker cover, <strong>be</strong>tween the valve springs. Remem<strong>be</strong>r, the compressionratio is controlled by the pis<strong>to</strong>n crown in ‘B’ series engines. As early engines had tinyvalves, I c<strong>an</strong>not imagine <strong>an</strong>yone w<strong>an</strong>ting <strong>to</strong> fit one <strong>to</strong> a MGB! The five main <strong>be</strong>aringheads have <strong>be</strong>tter combustion cham<strong>be</strong>r shapes, very wide <strong>an</strong>d little valve masking.‘B’ Series Through The Years.This shows how the power rose, <strong>an</strong>d bores got larger <strong>an</strong>d larger as years passed, <strong>an</strong>dtheir centres were put further <strong>an</strong>d further apart, siamesing the cylinder block bores,<strong>an</strong>d offsetting the big end journals <strong>to</strong> the bores.Model Year BHP Max Speed Bore/StrokeAustin A40 1954 42 65mph 65.5mm 89mmM.G. Magnette ZA 1954 60 81 73MGA 1500 1955 72 99 73Austin A55 Cambridge 1957 51 80 73Wolseley 1500 1957 50 80 73Morris Cowley 1957 42 65 65.5Morris Oxford 1957 55 74 73M.G. Magnette ZB 1958 68 87 73Austin A55 Mk2 1959 53 79 73Riley 4/68 1959 68 85 73MGA 1600 1959 80 101 75.4MGA Twin Cam 1960 108 113 75.4MGA 1600 Mk2 1961 93 103 76.2MG Magnette Mk4 1962 72 88 76.2Austin A60 1962 61 81 76.2MGB 1964 95 106 80.26Morris Marina 1.8 1972 85 95 80.26Morris Marina 1800 TC 1973 95 101 80.26Austin 1800 ‘S’ 1974 96 102 80.26(Note, the year quoted is that of the road test giving the maximum speed.)93

M.G. MGA Twin Cam engine,using the ‘B’ series cr<strong>an</strong>kcase.Recognize that oil filter <strong>an</strong>d itspipe <strong>an</strong>d those big ends?94

M.G. Magnette ZA <strong>Engine</strong> (1953-56)M.G. Magnette ZB <strong>Engine</strong> (1956-58)Interestingly, the arrival of the ZA with its shiny new BP15GA engine at the 1953London Mo<strong>to</strong>r Show, also saw the TF Midget with its 1250cc XPAG. The TF later gaineda 1466cc XPEG producing 63bhp, where as the ‘B’ series in the ZA only produced 60bhpfrom 1489cc at first. In m<strong>an</strong>y ways the engine in the Magnette saloon was very different<strong>to</strong> that most M.G. enthusiasts know, as in the MGA <strong>an</strong>d MGB. This very early ‘B’ had aby-pass oil filter, a real retrograde step considering the tradition of the ‘X’ series of thesaloon it replaced, in the ‘YB’. Because of the construction of the ZA with its forwardmounted engine, <strong>an</strong>d suspension cross mem<strong>be</strong>r, the pressed steel sump stuck right outthe front, as it did on the sister car of later years in the Wolseley 15/50, <strong>an</strong>d the ‘J’ typeMorris half <strong>to</strong>n v<strong>an</strong>. The ZA engine had a bore of 73mm <strong>an</strong>d the st<strong>an</strong>dard stroke of all‘B’ series, 89mm, with just 7.15 <strong>to</strong> 1 compression ratio, indicating the poor petrolquality about in those days. With its two SU H2 1 1/4"carburetters <strong>an</strong>d large MGoctagon on the polished air filter <strong>to</strong> carb aluminium casing, <strong>an</strong>d camshaft valve timingsof 5;45;40;10 with .322" lift, it produced the 60bhp at 4600rpm <strong>an</strong>d 76 lb/ft <strong>to</strong>rque at3000rpm. The air duct had a huge air silencer on it, dominating the engine. Exportversions had <strong>an</strong> oil bath type. There was a cast iron exhaust m<strong>an</strong>ifold, with <strong>an</strong>aluminium inlet bolted <strong>to</strong> it <strong>to</strong> give two hot spots. Inlet valves were 1.375" diameter<strong>an</strong>d exhaust 1.28", <strong>an</strong>d the dry clutch was 8" diameter. 1956 saw the full flow oil filterfitted, <strong>an</strong>d a pipe had <strong>to</strong> <strong>be</strong> run from the rear oil gallery <strong>to</strong> the filter, so it could feed backin<strong>to</strong> the main oil gallery. This pipe is <strong>an</strong> obvious afterthought, but did assist in fitting <strong>an</strong>oil cooler later. All the oil was now filtered all the time, <strong>be</strong>fore reaching <strong>an</strong>y <strong>be</strong>arings. InMay 1953 a <strong>be</strong>tter Weslake cylinderhead developed by Harry Weslake, was fitted <strong>to</strong> theZA, with improved ports. Early ZA’s may not have this fitted. M.G. complained overthe rocker adjusters in May 1954, <strong>an</strong>d these were lengthened <strong>an</strong>d of <strong>be</strong>tter quality.By ZA car num<strong>be</strong>r 18101, the petrol quality must have improved, or M.G. werelooking <strong>to</strong>wards their new MGA sportscar, <strong>be</strong>cause M.G. had the compression ratioraised <strong>to</strong> 8.3 <strong>to</strong> 1. Larger SU H4 1 1/2" carbs were fitted, <strong>an</strong>d power rose <strong>to</strong> 68bhp at5200rpm. M.G. had quite a h<strong>an</strong>d in the ‘B’ series, Eric Bareham the designer was oftenasked for modifications <strong>to</strong> them for use in M.G. cars. Larger inlet valves were fitted of1.5" diameter, along with thinner pis<strong>to</strong>n rings, double valve springs, <strong>an</strong>d solid skirtstronger pis<strong>to</strong>ns. It was fitted <strong>to</strong> the new MGA, then this <strong>be</strong>tter engine continued in themore flamboy<strong>an</strong>t ZB that followed as the BP15GC, from 1956 <strong>to</strong> 1958. At the same timeas the ZB, the Wolseley 4/44 with its XPAW engine was updated <strong>to</strong> the Wolseley 15/50in June 1956, with a 1489cc ‘B’ series, now almost a single carb ZB. 68bhp was a goodpower <strong>to</strong> weight ratio for the mid 1950’s, <strong>an</strong>d this was not lost on the M.G. sportscarenthusiasts. ‘Z’ Magnette production was 36,601.Fitting the 1622cc or 1798cc engine <strong>to</strong> a ZA/ZB is involved, for more informationsee under Mk4 Magnette later. Additional complications on these ‘Z’ cars is the need <strong>to</strong>use its sump <strong>an</strong>d oil pick-up, not <strong>to</strong>o much problem on the 1622cc engines as these arevery similar <strong>to</strong> the 1489cc ‘B’, <strong>an</strong>d only the sump & oil pick-up swap is required,though extra holes need drilling in the sump fl<strong>an</strong>ge if it is a later 16AA or 16GF engine.For the 1798cc swap the sump off the 1798’s rim needs welding <strong>to</strong> the lower half of the‘Z’s sump p<strong>an</strong>. You c<strong>an</strong> make the forward ‘Z’, ( J Morris v<strong>an</strong>, or Wolseley 15/50,) sumpfit a 1798cc engine, ( I have in the past,) but there are some close corners where onlyabout 1/16" of sump sits on the gasket. 1798cc five main <strong>be</strong>aring cr<strong>an</strong>kshafts have differentspacings for the six bolt holes that hold the flywheel on, so you c<strong>an</strong>not use your1489/1622 flywheel. The ‘Z’ sump also has <strong>an</strong> oil drain welded <strong>to</strong> the rear face of the95

BMC ’B’ SeriesA ‘B’ series for sale at <strong>an</strong> au<strong>to</strong>jumble. A check of its prefix showed it was a JU v<strong>an</strong> block, not a MG.MG ZA underbonnet area. The 1489cc engine sits well forward.96

BMC ‘B’ SeriesThe ZA engine , offside view.The MGA shared thr same ‘Z’ series, with a few more BHP. The ’Z’ has good access around its engine, the MGApoor access.97

sump, which the 1622/1798cc engines rear cr<strong>an</strong>kshaft webb will hit if you do not‘flatten’ it a little, ( proving cylinder bore centres did move outwards!)The starter mo<strong>to</strong>r on the Z’s sits higher up th<strong>an</strong> on the 1622cc or 1798cc engines, <strong>to</strong>clear the chassis frame. A 1798cc water pump has a longer shaft th<strong>an</strong> a 1489cc one.MGA 1500 <strong>Engine</strong> (1955-59)The ZA generously gave its engine <strong>an</strong>d running gear <strong>to</strong> the car M.G. had <strong>be</strong>entrying <strong>to</strong> get out <strong>an</strong>d sell for a few years, in August 1955. The 1489cc ‘B’ series BP15GB,was a similar engine but with p<strong>an</strong>cake air filters, <strong>an</strong>d was the M.G. improved unitabove specially produced for the MGA, having used the ZA Magnette as a test <strong>be</strong>d. Amajor difference was the MGA ‘normal’ sump, sitting <strong>be</strong>hind the suspension crossmem<strong>be</strong>r, <strong>an</strong>d requiring a new oil pick-up, that it gained from the run of the mill Austin<strong>an</strong>d Morris cars. It produced 68bhp at 5200rpm, later <strong>to</strong> rise <strong>to</strong> 5500 as the BP15GD with72bhp at 6000rpm in 1956, with its improved cr<strong>an</strong>kshaft. In the low slung sports car itperformed well, giving 0 <strong>to</strong> 60 in about 14 seconds, <strong>be</strong>tter th<strong>an</strong> that of 16.5 for the TF itreplaced. The 68bhp version was fitted <strong>to</strong> the ZA Magnette in 1956, <strong>an</strong>d in 1957 <strong>to</strong> theMorris Minor based Riley 1.5. The cr<strong>an</strong>kshaft was very strong, made of EN16 steel,with 1.875" diameter big ends <strong>an</strong>d 2" diameter main <strong>be</strong>arings, of generous length, <strong>be</strong>ingcounterbal<strong>an</strong>ced with shell <strong>be</strong>arings, now located by lugs at the cap joints. The valvesprings had <strong>be</strong>en <strong>be</strong>efed up on the power increase in the MGA & ZA, <strong>an</strong>d were double,<strong>to</strong> permit higher rpm, where as on the lower revving Austin/Morris there were singlesprings. Normal BMC cars used a 7.2 compression ratio, for M.G. this was increased <strong>to</strong>8.3 <strong>to</strong> 1. All MGA’s use the same camshaft, with a skew gear on the rear end <strong>to</strong> drive amech<strong>an</strong>ical tachometer, valve timings are 16;56;51;21, with a lift of .355". This camshaftcontinued with the early MGB. The only two other cars that used this tacho-drive wasthe Riley 1.5 (15R,RA,RB engine,) <strong>an</strong>d Riley 4/68 Farina ( 15RA & RB,) <strong>an</strong>d 4/72 until1966, (16RA,) both using a close copy of this MGA 1489cc engine in 68bhp trim.EX182, LeM<strong>an</strong>s 24 hour <strong>Engine</strong> 1955.Used a bal<strong>an</strong>ced ‘B’ series engine of 1489cc as in the ZA Magnette, st<strong>an</strong>dard 8"clutch, with a modified cylinderhead as per-BP15GD, two SU fuel pumps, twin SU1.75" H6 carburetters, fitted with trumpets ( ram stacks) not air cle<strong>an</strong>ers, with a cold airfeed, oil cooler, mildly tuned <strong>to</strong> give 82bhp on a 9.4 <strong>to</strong> 1 compression ratio. Rather abl<strong>an</strong>d engine when you consider how famous the car is, possibly built for reliabilityrather th<strong>an</strong> speed, ie <strong>to</strong> finish the 24 hour course. Two of the cars finished, 5th & 6th intheir class. Alas no one remem<strong>be</strong>rs this, as a Mercedes crashed in<strong>to</strong> the crowd killingm<strong>an</strong>y specta<strong>to</strong>rs.MGA 1600 <strong>Engine</strong>, (1959-61).By April 1958 the MGA needed a boost in power, <strong>an</strong>d the M.G. ‘B’ series was re-cored givingthe cylinders thicker walls, allowing it <strong>to</strong> <strong>be</strong> bored out <strong>to</strong> 1588cc with a 75.4mm bore <strong>an</strong>d the89mm stroke. The engine was otherwise unch<strong>an</strong>ged from the 1489cc BP15GD, now <strong>be</strong>ingcalled a 16GA. This gave 80bhp at 5600rpm with 87lb/ft <strong>to</strong>rque. It was called the MGA 1600,<strong>an</strong>d the cylinder block was bored <strong>to</strong> this 1588cc size for the MGA twin camshaft engine, <strong>an</strong>dthis capacity is unique <strong>to</strong> M.G. as no other marque used it. See also Twin Cam.98

MGA 1600 Mk2 <strong>Engine</strong> (1961-62)April 1961 saw the introduction of a full redesign of the ‘B’ series. Long runs at highrpm on the new mo<strong>to</strong>rways, the M1 opening in 1959, had shown the normal salooncar’s engines were having problems. This 1622cc 16GC engine was again first fitted <strong>to</strong>a M.G. It updated the MGA <strong>an</strong>d gave it quite a boost in power, up from 72bhp <strong>to</strong> amassive 93bhp at 5500rpm with 97lb/ft <strong>to</strong>rque, from <strong>an</strong> 8.9 <strong>to</strong> 1 compression ratio. Thestroke remained at 89mm, the bore opened out <strong>to</strong> 76.2mm, by re-coring the cylinderscentres further apart <strong>an</strong>d off-setting the bores <strong>to</strong> the big end journals, requiring newcon rods. This was a much stronger block th<strong>an</strong> the 1489/1588 one. It had a newcr<strong>an</strong>kshaft with the same diameter main <strong>an</strong>d big ends as the original 1200/1489ccengines, but the main <strong>be</strong>arings were now narrower, down from 1.375" <strong>to</strong> just 1.25", <strong>to</strong>get the bigger bores in. The <strong>be</strong>aring material was improved copper-lead alloy <strong>to</strong> copewith the extra power, though when the engine was opened up <strong>to</strong> 1798cc the narrowermain <strong>be</strong>arings would cause trouble. A new cylinderhead with improved ports, largervalves <strong>an</strong>d stronger springs with <strong>an</strong> improved distribu<strong>to</strong>r, completed the engine. Inletvalves were now 1.5" diameter, <strong>an</strong>d the exhaust 1.28". Like the Midget, the gearboxgained outer ribs <strong>to</strong> strengthen it. This engine gave the MGA cracking perform<strong>an</strong>ce.The MGA cylinderhead was modified <strong>to</strong> improve airflow, but <strong>be</strong> warned that theengine num<strong>be</strong>rs quoted relate <strong>to</strong> the cylinder block, <strong>an</strong>d heads c<strong>an</strong> easily <strong>be</strong> swappedabout. From BP15GB 4045 the exhaust ports were enlarged a little. BP15GA 17151onwards had larger inlet ports as well.In June1962 the MGA bowed out <strong>to</strong> the new, bigger MGB, after a <strong>to</strong>tal of 98,970.A Record Breaking <strong>Engine</strong> MGA (EX179)MGA Twin Camshaft <strong>Engine</strong> (1958-60) – Originally me<strong>an</strong>t for theZA Magnette!M.G. were up <strong>to</strong> their tricks again, the idea of using common components had <strong>be</strong>encircumnavigated by 1958, <strong>an</strong>d both Morris <strong>Engine</strong>s <strong>an</strong>d the Austin Design Office had ago at a twin overhead camshaft engine for the MGA, <strong>an</strong>d that chosen was of the ADO,in July 1958. A twin-Cam engine was the idea of Gerald Palmer, <strong>an</strong>d had <strong>be</strong>en though<strong>to</strong>f initially as <strong>an</strong> engine <strong>to</strong> offer with the MG ZA Magnette. This would have <strong>be</strong>en the‘GT’ version in modern parl<strong>an</strong>ce. The Morris version was designed from firstprinciples, on a cle<strong>an</strong> sheet of paper, but Austin had kept costs down by using <strong>an</strong> inhousecylinder block, that of the 1498cc ‘B’ series. Breathing was always the limit on<strong>an</strong>y engine’s power output, so <strong>to</strong> improve the ‘B’ series it gained a completely newdohc cross-flow cylinder head of aluminium alloy. To fit the dohc head <strong>to</strong> the ‘B’ seriescylinder block, the studs were slightly re-positioned. So successful was the design thatit would rev quicker that some people could take their foot off the power, <strong>an</strong>d it wasvery easy <strong>to</strong> over-rev it <strong>an</strong>d damage the internals. The engine required 100 oct<strong>an</strong>e fuelor it pinked, or worse, overheated, <strong>an</strong>d the correct grade of cooler running spark plugfor fast driving, N7YC, ( was N58RS.) In normal use with 100 oct<strong>an</strong>e petrol, a ChampionN3 would suffice. If fuel of less th<strong>an</strong> 100 oct<strong>an</strong>e is used, Lodge RL47 plugs wererecommended, <strong>an</strong>d the engine will run on. The engine got itself a bad name formelting pis<strong>to</strong>ns, but this was more <strong>to</strong> do with inexperienced drivers <strong>an</strong>d mech<strong>an</strong>icswho did not underst<strong>an</strong>d the me<strong>an</strong>ing of accurate timing, correct plug grades, or rpmlimit red lines, etc. The 9.9 <strong>to</strong> 1 compression ratio did not help, <strong>an</strong>d the last few engines99

were found <strong>to</strong> last longer <strong>an</strong>d <strong>be</strong>have <strong>be</strong>tter when it was dropped <strong>to</strong> the normal M.G.ratio of 8.3:1, ( from engine num<strong>be</strong>r 2251.) The 8.3 compression ratio dropped thepower figures from 108bhp <strong>to</strong> 100bhp @ 6700rpm. Nought <strong>to</strong> 60mph in 11.5 seconds in1958 in a car of the price of the MGA Twin Cam was fabulous, ( fac<strong>to</strong>ry figure, Mo<strong>to</strong>rsays it was 9.1 seconds, Au<strong>to</strong>car says 13.3.) Zero <strong>to</strong> 100mph <strong>to</strong>ok 30 seconds. The oilconsumption of 1500mpg mirrored that of the early 1950’s Jaguar XK120’s, ie awful.The car did <strong>an</strong> average of 21mpg.The engine used a normal 1489cc cylinder block, with the water passages re-cored<strong>to</strong> allow bigger bores of 75.414mm, with the 88.9mm stroke giving 1588cc capacity. Itwas fitted with a rib<strong>be</strong>d cast aluminium alloy sump, cylinderhead, <strong>an</strong>d front casingcarrying the new position for the distribu<strong>to</strong>r. The ‘camshaft’ of the old block nowfulfilled the use of a jackshaft ( called a half-speed-shaft by MG,) <strong>to</strong> drive the oil pumponly. This is gear driven, not chain driven, so rotates in the opposite direction <strong>to</strong> the oldcam. The engine has fully floating gudgeon pins in solid skirt pis<strong>to</strong>ns <strong>an</strong>d a 9.9 <strong>to</strong> 1compression. The head carried two cast iron camshafts, with 20;50;50;20 valve timings,.375" lift, the inlet valves <strong>be</strong>ing 1.6" diameter <strong>an</strong>d exhaust valves 1.44" dia., ( sodiumcooled for racing,) both set at 45 degree <strong>an</strong>gle in the head, with double valve springs.Both cams are identical, appart from the timing slot; <strong>an</strong>d both have a hexagon cast in <strong>to</strong>enable them <strong>to</strong> <strong>be</strong> turned when timing. The head, with renewable steel valve seatinserts cast in, was a cross-flow hemispherical combustion cham<strong>be</strong>r head, ( hemihead.)The exhaust was on the normal ‘B’ side, but with two huge SU H6 1 3/4"carburetters with p<strong>an</strong>cake air filters <strong>an</strong>d a cold air feed duct on the other side.Interestingly, one of the inlet m<strong>an</strong>ifold securing nuts lives INSIDE the m<strong>an</strong>ifold. Tofeed fuel <strong>to</strong> the two carbs it had a high capacity SU electric fuel pump. To hold the solidskirt aluminium alloy, convexed head pis<strong>to</strong>n in it had ‘H’ section forged steel con-rodswith <strong>an</strong>gled split big ends from the ohv engine. The f<strong>an</strong> was of five blades unlike thenormal two or four of other cars. The engine was a BC16GB in BMC engine num<strong>be</strong>ring.All you could see under the open bonnet was two massive polished alloy rockercovers, it must have <strong>be</strong>en a swine <strong>to</strong> work on.Early cars used the MGA/ZA Magnettes 4psi cooling system, but later this rose <strong>to</strong>7psi. Again the distribu<strong>to</strong>rs had a vacuum adv<strong>an</strong>ce from the MGA/ZA, ( 40510B,) butthis was soon deleted due <strong>to</strong> ignition timing w<strong>an</strong>der, not a good thing on such a fussyengine, very prone <strong>to</strong> melting pis<strong>to</strong>ns! The later distribu<strong>to</strong>r ( 40718A) was retro fitted <strong>to</strong>m<strong>an</strong>y earlier cars. From engine No.1523 the ignition marking were on the distribu<strong>to</strong>r, (22-26 degree adv<strong>an</strong>ce @ 3000rpm.)At engine 1587 cast iron tappet bore liners were introduced, due <strong>to</strong> the bucketspicking up on the original aluminium bores. These liners were secured by a grubscrew.MG had some fun with the tappets themselves, as the original 1 1/4" longversion could tilt in their bores at high rpm, <strong>an</strong>d locking up. This broke the camshaft,then leading <strong>to</strong> a blown up engine! From engine num<strong>be</strong>r 1087 they were lengthend <strong>to</strong> 11/2" long. The camshafts were chain driven off the ‘half-speed-shaft’, itself driven by agear on the cr<strong>an</strong>kshaft nose. It was a long chain, <strong>an</strong>d could mis<strong>be</strong>have if not tensioned/timed correctly. MG went <strong>to</strong> great lengths <strong>to</strong> ensure all owners/mech<strong>an</strong>ics knew this,<strong>an</strong>d issued a four page ‘service memor<strong>an</strong>dum’ on the procedure, written by BobSeymour, MG’s Twin-Cam running expert in the field.The little end bushes were modified at engine No.710, <strong>to</strong> improved the oilways. MGdid not trust the pinch-bolt little-end arr<strong>an</strong>gement on the ohv ‘B’ series. <strong>Engine</strong>s up <strong>to</strong>No. 445 had rough turned chromed <strong>to</strong>p rings, with a cast iron oil-scraper ring, with100

drain holes directly underneath in the pis<strong>to</strong>n skirt. From No.446 <strong>to</strong> 605, the oil controlring was improved <strong>to</strong> a twin-segmented ( twin-rail,) oil ring, with no drain holes. FromNo.606 a new pis<strong>to</strong>n was fitted, with a chromed <strong>to</strong>p ring, <strong>an</strong>d the segmented oil controlring, but the spacings differed.From engine No.2060, exp<strong>an</strong>ders were fitted <strong>be</strong>hind theoil control segments. All this was <strong>to</strong> try <strong>to</strong> control the high oil consumption. At engineNo.315, the gear ratios on the half-speed-shaft drive <strong>to</strong> the oil pump were altered, <strong>to</strong>speed up the pump.There were quite a few niggly things with the Twin Cam. On early cars, Nos 504 <strong>to</strong>531, the starting h<strong>an</strong>dle dog could foul the steering rack. Dynamo brackets wouldcrack, MG issued stronger cast iron items. The gearbox breather r<strong>an</strong> very hot, <strong>an</strong>d if thebreather blocked, oil leaks were the result. If you eventually decided the twin-camengine was <strong>to</strong>o much trouble, MG would fit a ohv 1588cc engine for you.The Twin Cam production ended in April 1960, after 2111 cars. A 1588ccdevelopment engined Twin Cam had <strong>be</strong>aten a 2639cc ‘C’ series engined pro<strong>to</strong>typeHealey 100/6 in the USA in August 1956, in a record attempt. The M.G. EX179 did170mph, <strong>an</strong>d the Healey did just 152mph.Cromp<strong>to</strong>n-L<strong>an</strong>chester Lecture, by W.V. Appleby, 1960This lecture by Bill Appleby of the ADO, <strong>an</strong>d responsible for the ‘B’ series, tells us alot about this engine, <strong>an</strong>d particularly that for the MGA. The cylinder block is made ofcast iron <strong>to</strong> the British St<strong>an</strong>dard, (BS) 1452-17, with the water jacket down <strong>to</strong> just <strong>be</strong>lowthe track of the pis<strong>to</strong>n rings in the bore. Two locating holes are machined first, in thesump fl<strong>an</strong>ge of the casting, <strong>an</strong>d reamed accurately, <strong>an</strong>d from then on they are used <strong>to</strong>locate the block for all further machining. You c<strong>an</strong> see these holes, they seemed <strong>to</strong> havelittle use when the engine was in service, now we know! Bores are not honed, but wirebrushedby machine, then rolled <strong>to</strong> flatten the ridges. A scroll rear cr<strong>an</strong>kshaft oil sealwas thought satisfac<strong>to</strong>ry for the engine’s use, <strong>an</strong>d runs with <strong>an</strong> .008" clear<strong>an</strong>ce.Camshaft <strong>be</strong>arings are lined with babbitt in the steel backed shells, as unlike the early‘A’ series, it does not run direct in the block iron.Cylinder heads are made of the same metal, with a patent Weslake shapecombustion cham<strong>be</strong>r <strong>an</strong>d porting. The cham<strong>be</strong>r is heart shaped, so that incomingmixture is directed at the central spark plug. The wall is brought round <strong>be</strong>tween theinlet <strong>an</strong>d exhaust <strong>to</strong> protect the inlet gases from the hot exhaust valve, <strong>an</strong>d reducing theamount of ignition adv<strong>an</strong>ce required. The cr<strong>an</strong>kshaft is made of EN16, 55 <strong>to</strong>n steel witha safety fac<strong>to</strong>r of 4 <strong>to</strong> 1. Radii on journals must <strong>be</strong> kept free of <strong>to</strong>olmarks, or stress c<strong>an</strong> <strong>be</strong>induced <strong>an</strong>d the shaft break.Two holes per <strong>be</strong>aring are drilled for oil delivery. Con-rodsare of 55 <strong>to</strong>n alloy steel of ‘H’ cross section, with a clamped gudgeon pin. Big end shell<strong>be</strong>arings are of steel backed copper-lead alloy, with a thin lining of tin or lead-indium,capable of loads up <strong>to</strong> 9000 lb/in sq. The ‘B’ series has a loading of 3000 lb/in sq. The<strong>to</strong>uring engines have split skirt Lo-ex aluminium pis<strong>to</strong>ns, but MG use solid skirtpis<strong>to</strong>ns that need <strong>an</strong> extra ‘half-thou’ running clear<strong>an</strong>ce, <strong>an</strong>d the rings are thinner th<strong>an</strong>the <strong>to</strong>uring engine. Oil rings are designed <strong>to</strong> give 6000 miles per gallon (mpg) of oil at40 mph, <strong>an</strong>d 500 mpg of oil at 80 mph, later improved <strong>to</strong> 2000mpg at 80 mph. The <strong>to</strong>pring is chrome plated for longer life.The camshaft lo<strong>be</strong> shape is based on the sine curve, with complex hardening of thelo<strong>be</strong>s, journals <strong>an</strong>d sprockets. The cam followers are chilled cast iron, <strong>an</strong>d their centre is101

An open view of the BMC ‘B’ series under the bonnet of the MGA. This actual drawing is that of EX182 withthe 1489cc unit fitted. Careful inspection will show there is no oil pipe or oil filter bowl. Racing cars often usedry sumps, seperate oil t<strong>an</strong>ks, <strong>an</strong>d oil coolers. Copyright is that of au<strong>to</strong>car.102

‘B’ series in the MGB Mk1, 1798cc three main <strong>be</strong>aring unit. Shown with <strong>an</strong> oil cooler, paper air filter elements,dynamoe, <strong>an</strong>d the gearbox straight out of the MGA/MG MagnetteMk3 Farina. In the MGB ‘B’ series <strong>be</strong>camealmost as long lived as <strong>an</strong>y engine ever could. Simple, robust, easy <strong>to</strong> repair, plenty of reasonably priced spares,idealfor DIY jobs. Did Appleby, Bareham, <strong>an</strong>d Rix ever think it would live so long back in 1953?103

slightly out of line with the lo<strong>be</strong>, with a .002" dome, <strong>to</strong> ensure rotation <strong>an</strong>d even wear.Tappet <strong>an</strong>d lo<strong>be</strong> maximum loads are in the region of 190,000 lb/in sq. Pushrods aresolid, but c<strong>an</strong> deflect up <strong>to</strong> 5/64" on the MGA at 6100 rpm, with a load of 560lb, ( 400 lbon <strong>to</strong>uring engines.) The rockers have a ratio of 1.406:1, increasing lift a little. There is aload of 960lb per rocker on the MGA engine, ( 700lb on the <strong>to</strong>uring unit,) <strong>an</strong>d they aremade from malleable cast-iron.Inlet valves are made from Silchrome ( EN52,) <strong>an</strong>d exhaust from XB (EN59). Forhigh perform<strong>an</strong>ce in the Twin Cam these are stellited XB, or KE956 steel. Inlet valvesteel has a tensile strength of 4 <strong>to</strong>n/in sq; XB 5 <strong>to</strong>n/in sq; <strong>an</strong>d KE965 16 <strong>to</strong>n/in sq.The oil pump of the MGA delivers 3 gallons of oil per minute at 1000rpm, <strong>an</strong>d isdriven at half engine speed. The water pump moves 8.8 gallons per minute at 4000rpm. The flywheel is 17-<strong>to</strong>n cast iron. Interestingly the dynamo is a 22 amp/hr type,runs at 1.698 engine speed, but with all services running 22.6 amps are required, a netloss!Tuning the MGAThe MGCC MGA Register has a ‘BMC Special Tuning’ leaflet for this model, full ofgood information, num<strong>be</strong>r C-AKD 819E.Valve Seat Inserts <strong>be</strong>fore Unleaded?It was a very tatty MGA 1500, in about 1966, that I assisted a friend <strong>to</strong> get up <strong>an</strong>drunning. Such cars in those days were worth little money, <strong>an</strong>d neither of us, as youngRAF servicemen, had <strong>an</strong>y spare cash. He had paid £10 for it, as a non-runner, <strong>an</strong>d hew<strong>an</strong>ted it <strong>to</strong> impress the girl he was courting. It would not fire up at all, <strong>an</strong>d havingflattened the battery twice, he called me in. I checked for fuel <strong>an</strong>d a spark, <strong>an</strong>d foundboth. So we charged up his battery, then I <strong>to</strong>wed him around the RAF station with mySeries ‘E’ 1940 Morris 8hp. Round <strong>an</strong>d round we went, with no sign of <strong>an</strong>y life. I thenchecked over his work, he having fitted new points, etc. The age old trick of simplyputting all the plug leads on wrong, 180 degrees out, was the fault. I corrected this, <strong>an</strong>doff we went again. Within 20 yards the engine burst in<strong>to</strong> life, then a split second laterthere was a huge b<strong>an</strong>g. As the cloud of dust settled around the now roaring MGA, Isaw the entire exhaust system had split wide open, covering one <strong>an</strong>d all in black soot.The system had filled up with petrol as we drove round, <strong>an</strong>d once the engine fired up,BOOM!! The s<strong>to</strong>ry does not end there, as he found a good system on <strong>an</strong>otherab<strong>an</strong>doned car, <strong>an</strong>d had it all adapted <strong>an</strong>d fitted for the weekend run <strong>to</strong> see the younglady. He had even cle<strong>an</strong>ed the car <strong>an</strong>d screwed the floorboards back down. On theSunday I had a call <strong>to</strong> <strong>to</strong>w him in. He had conked out about 3 miles up the A1 on hisreturn. The car refused <strong>to</strong> start, so in the end a compression check show NIL on allcylinders. On removing the head, there I saw a set of exhaust valve seat inserts jinglingloose on their valves, on what was obviously a reconditioned head, once! He had runout of water, boiled, kept going, raised the engines temperature so high, <strong>an</strong>d they hadall fallen out. We fitted a cylinder head from a dumped 1489cc Morris Oxford, <strong>an</strong>d offhe went on his next adventure.104

Back <strong>to</strong> Large M.G. Saloons.M.G. Magnette Mk3 <strong>Engine</strong>, (1958 <strong>to</strong> 61)The ‘B’ series was in use in lots of cars, one <strong>be</strong>ing perhaps a controversial M.G.model. No matter what your views, the car is part of M.G. his<strong>to</strong>ry <strong>an</strong>d was part of ar<strong>an</strong>ge of M.G’s for the public. This model has the 1489cc 15GE engine, a very closerelative <strong>to</strong> the MGA 1500 engine of 68 bhp, the engine <strong>be</strong>ing shared with a sister car, theRiley 4/68, <strong>an</strong>d a tiny Riley 1.5 model based on a Morris Minor floor p<strong>an</strong>, ( with hugedrum brakes.) The Mk3 has two SU HD4 1 1/2" carburetters on <strong>an</strong> engine that isidentical <strong>to</strong> the ZB Magnette, the carbs <strong>be</strong>ing the only difference, <strong>an</strong>d have a rub<strong>be</strong>rdiaphragm for mixture <strong>an</strong>d choke control, not fitted <strong>to</strong> <strong>an</strong>y other M.G. ( But fitted in aHD6 size <strong>to</strong> Jaguar,Rover <strong>an</strong>d Rolls Royce cars.) It has a 8.3 <strong>to</strong> 1 compression <strong>an</strong>d the68bhp is at 4800 rpm, <strong>an</strong>d 85lb/ft <strong>to</strong>rque at 3300rpm, the camshaft <strong>be</strong>ing a bit softer forsaloon use, <strong>an</strong>d of 5;45;40;10 valve timings, with a lift of .322". The normal Austin A60versions have the st<strong>an</strong>dard BMC cam of 5;45;45;5 with .0312" lift, <strong>an</strong>d 60bhp. The inletvalve is 1.5" diameter, <strong>an</strong>d the exhaust 1.28". The engine has <strong>to</strong> work very hard indeed<strong>to</strong> pull the 23cwt saloon, a bit like the VA One <strong>an</strong>d a Half Litre.At engine num<strong>be</strong>r 15GE8067 the camshaft timing was altered <strong>to</strong> TDC;50;35;15, which was moving it all alongfive degrees <strong>to</strong> improve <strong>to</strong>rque, something they did with the st<strong>an</strong>dard M.G. Midgetcam timing on the M.G. Metro 1300 later. Oil pressure was 75psi, not the normal 50psiof the single carb models. The Mk3 did not use the tachometer drive off the cam, so itwas left undrilled. The Riley cars did use it. 2889 ‘Di Tella’ Farina Magnette 1622’s werebuilt in Argentina <strong>be</strong>tween 1960 & 1967. These were either single or twin carburetted,with plastic dash boards.M.G. Magnette Mk4 <strong>Engine</strong>, (1961-68)In Oc<strong>to</strong><strong>be</strong>r 1962 the Mk4 Magnette gained the MGA 1600 Mk2 engine, but detuned<strong>to</strong> 72bhp in the interests of longer life <strong>an</strong>d mid-r<strong>an</strong>ge <strong>to</strong>rque. Camshaft, valve sizes <strong>an</strong>dcarburetters remained as the Mk3. With bore <strong>an</strong>d stroke of 76.2mm <strong>an</strong>d 89mm, <strong>an</strong>d a8.3:1 compression, the engine produced 72bhp at 5200rpm with 89 lb/ft <strong>to</strong>rque. Thef<strong>an</strong> had four blades fitted from Novem<strong>be</strong>r 1964, two previously. In Novem<strong>be</strong>r 1966 the1622cc engines had common parts from the MGB/Marina 1800 fitted <strong>to</strong> cut down costs<strong>an</strong>d s<strong>to</strong>cks. The sump was enlarged <strong>to</strong> one side <strong>to</strong> accommodate the bulge in the blockthat now housed the bigger MGB oil pump, <strong>an</strong>d was in fact a MGB sump, <strong>an</strong>d the MGBwater pump was fitted. The engine was prefixed 16GF. The Riley 4/72 lost itscamshaft/cable driven MGA/early MGB tacho on its 16RA engine, <strong>an</strong>d had <strong>an</strong>electronic impulse unit fitted. It <strong>to</strong>o then had the common 16GF engine, now fitted <strong>to</strong>both Farinas. Both cars <strong>be</strong>nefit from a 88 degree thermostat, as they tend <strong>to</strong> run cool onthe st<strong>an</strong>dard 82 degree one. The 1622cc engine gave the large saloon a decentperform<strong>an</strong>ce, it could <strong>to</strong>uch 95mph if you were brave! If you wish <strong>to</strong> fit a MGB 1798ccengine <strong>to</strong> a Farina Magnette, ( or <strong>to</strong> a MGA come <strong>to</strong> that,) try <strong>to</strong> locate a 18G or 18GAMGB three main <strong>be</strong>aring engine. These will bolt directly on<strong>to</strong> the Farina/MGA’sgearbox. The later five main <strong>be</strong>aring unit requires the smaller car’s rear engine plateturning out on a lathe <strong>to</strong> take the rear neoprene, ( <strong>an</strong>d much improved,) cr<strong>an</strong>kshaft oilseal, <strong>an</strong>d the old oil drain on the plate brazing up, <strong>an</strong>d the smaller car’s gearbox firstmotion shaft shortening by 3/4", <strong>an</strong>d, a small 1622/1498cc engines sintered bronzebush fitting in<strong>to</strong> the spigot <strong>be</strong>aring hole in the rear of the cr<strong>an</strong>k. The flywheels of thesmaller engines have different fixing bolt spacings <strong>to</strong> the later five main <strong>be</strong>aring 1798cc,so the MGB flywheel has <strong>to</strong> <strong>be</strong> used, with it drilled accurately <strong>to</strong> take the 8" Farina105

BMC ‘B‘ SeriesThe 1622cc engine fitted <strong>to</strong> a Mk4 MG Magnette, a close copy of the 1622cc MGA 1600 Mk2.Difficult <strong>to</strong> pho<strong>to</strong>, a hidden MGF ‘K’ series engine. <strong>How</strong> do you show it off?106

BMC ‘B’ SeriesThe MGB 1798cc engine above found itself in the Morris Marina 1800TC <strong>be</strong>low, the only major difference wasthe cr<strong>an</strong>kshaft, MG one was forced, Morris one was flowcast. Little things like oil feed <strong>to</strong> the rockers could causeproblems if swapping heads.107

Fast MGsThe MGA Twin Camshaft engine, snug in its bay.A RoverK16 engine in a special MG Midget.108

clutch cover. Use a Farina clutch plate, so it will match the gearbox splined first motionshaft.Yes, quite a bit of modification.When the other single carburetter Farinas gained the MGB engine parts, they were called16AA engines. The Mk3 <strong>an</strong>d Mk4 Magnette produced 30,996 cars, very few survive. Somewere au<strong>to</strong>matic cars, using the Borg Warner type 35 au<strong>to</strong>box, the same unit as in the MGBau<strong>to</strong>matic.Only 300 were made in their last year of production.Almost Fitted <strong>to</strong> M.G.s1622cc Compliments of BMC AustraliaAnd the Blue Streak1959, the year that BMC introduced the Mini, saw the engine design departmentproduce <strong>an</strong> updated ‘B’ of 1622cc. It was built by the Australi<strong>an</strong> BMC Comp<strong>an</strong>y, as theythought the 1489cc <strong>to</strong>o small for their needs. The engine was thoroughly tested downunder, but they went one stage further, by adding two cylinders <strong>to</strong> the block <strong>an</strong>dcalling it the 2433cc Blue Streak Six, keeping the same 1622cc bore centres, cylinderbore, <strong>an</strong>d stroke. This unit was what they needed <strong>to</strong> fit the the Farina A60 Austin <strong>an</strong>dWolseleys they assembled there. Moving the engine back a bit, <strong>an</strong>d the frontsuspension cross mem<strong>be</strong>r forward 1", <strong>to</strong> improve weight distribution, the six cylindersold against the big Americ<strong>an</strong> ‘economy’ sixes, <strong>an</strong>d vee eights, as the Austin Freeway<strong>an</strong>d Wolseley 12/80. BMC in the UK did not w<strong>an</strong>t <strong>to</strong> know, having tried the same ideawith a six from 1489cc earlier. So it <strong>be</strong>came a small six peculiar <strong>to</strong> Australia, producing80bhp at 4800rpm on a single SU HS2 carburetter. A ‘B’ that never officially got in<strong>to</strong> <strong>an</strong>M.G. This six cylinder is not a ‘C’ series, but one was borrowed <strong>an</strong>d used in the MGC inthe pro<strong>to</strong>type for measurements, <strong>an</strong>d road testing the new <strong>to</strong>rsion bar ifs. M.G. calledthis 2433cc the ‘light-six’ ‘B’ series.Very Nearly a 2 ltr MGB. For the MGB in 1972, <strong>an</strong> ‘O’ series SOHC engine had <strong>be</strong>endeveloped <strong>to</strong> fit the car. It was later in use as a 1700cc <strong>an</strong>d a 1994cc single ohc in theMorris Marina, so only a rear engine plate <strong>an</strong>d flywheel <strong>to</strong> suit the MGB gearbox wasneeded. Work had <strong>be</strong>en done on this ‘B’ series special, <strong>to</strong> ‘Federalise’ it <strong>to</strong> maintain theUSA sportscar market. See ‘O’ series later. A version of the ‘O’ series <strong>be</strong>came the RoverM16 engine.Valve RecessionThe plethora of valves available for the ‘B’ series once caused a friend with a Mk3Magnette problems. He de-coked his engine, <strong>an</strong>d used spare valves from his box ofsecond h<strong>an</strong>d valves <strong>to</strong> replace those of poor condition. Once ground in, all appearedwell. He came <strong>to</strong> me as he seemed <strong>to</strong> <strong>be</strong> const<strong>an</strong>tly having <strong>to</strong> adjust the exhaust tappetclear<strong>an</strong>ces, they kept closing up. He had used four, softer, inlet valves as exhaustvalves........!!!!!!! The word parsimonious comes <strong>to</strong> mind.109

Melted WiresA friend with a Mk3 Magnette was doing <strong>an</strong> early morning service of his car. Withsome friends he was off on holiday that afternoon. He ch<strong>an</strong>ged the oil, oil filter, f<strong>an</strong> <strong>be</strong>lt,points, plugs, <strong>an</strong>d condenser. For good measure he even greased the king-pins. Allgaps were correct, <strong>an</strong>d he went <strong>to</strong> try <strong>to</strong> start the car. It just wound over on the starter,with nothing else happening. He wound it over so long, oil pressure came up on thegauge! My help was requested, <strong>an</strong>d I guessed he had left the ro<strong>to</strong>r arm out, a commontrick we have all fallen for. But no, it was in situ. Simple things were checked first, fuel,yes, spark, NO. No spark at all. Then I <strong>to</strong>uched the spade terminal on the coil <strong>to</strong> checkfor the old problem of the terminal on the coil coming loose on its rivet. Ow! The wirewas hot, <strong>an</strong>d the plastic sheathing melted on<strong>to</strong> my skin, <strong>an</strong>d burnt. There was a deadshort somewhere, so he switched off the ignition.On older types of Lucas points, there is a fibre washer separating the two halves ofthe ignition points in the distribu<strong>to</strong>r. If you forget <strong>to</strong> fit it on the pivot, the two halveshave metal <strong>to</strong> metal contact. He had forgotten it (it was still in the little box). Theignition system simply r<strong>an</strong> <strong>to</strong> earth, no wonder there was no spark, <strong>an</strong>d a melted wire.I ended up making a new coil <strong>to</strong> distribu<strong>to</strong>r wire for him, <strong>an</strong>d fitting the washer in itscorrect location.On later points, the quick-fit type, owners often put the wireconnection under the nut on the pole, <strong>an</strong>d not under the nylon insula<strong>to</strong>r. If you do this,the system is earthed.Oily MessThe 1200cc, 1489cc, 1588cc, <strong>an</strong>d 1622cc ‘B’ series with the full-flow oil filter c<strong>an</strong>cause problems. To get the full oil flow through the filter, <strong>an</strong> extra pipe was run fromthe rear oil gallery <strong>to</strong> the filter bowl. You see it above the starter mo<strong>to</strong>r. What m<strong>an</strong>yowners do not realise is, the pipe actually connects <strong>to</strong> a small alloy casting above thesteel bowl holding the element. It <strong>to</strong>o has <strong>an</strong> ‘O’ ring oil seal <strong>be</strong>tween it <strong>an</strong>d the cylinderblock. So on a filter ch<strong>an</strong>ge, two seals are provided in the replacement filter box. Thethin one goes above the steel bowl, the other above the pipe connec<strong>to</strong>r. Some filtershave three seals, a thick one is for the early cars with the by-pass filt110

The five main <strong>be</strong>aring cr<strong>an</strong>kshaft of the later 1798cc ‘B’ series engine, a very full sump when compared <strong>to</strong> a1489/1622cc sump. Note that big ends are now horizontally split, a stronger arr<strong>an</strong>gement. Not so clear here, butthat side-valve Austin 12/4 of 1932 still had its effects on this engine, as the ‘B’ copied its cr<strong>an</strong>kshaft, though thebore centres have moved. To accomaodate this the big ends are offset from then cylinder bores, just noticeable onsmall 1498cc side view.111

Chapter SevenA Big ‘B’ Series <strong>Engine</strong>MGB & MGB GT Mk1 <strong>Engine</strong> ( 1962-67)In 1960, the same year that Austin developed a diesel version of their 1489cc ‘B’series, the design office had <strong>be</strong>en busy enlarging the 1622cc version as it was realisedthe 1622cc MGA 1600 Mk2 engine might have its work cut out pulling the new, bigger,more roomy, <strong>an</strong>d somewhat softer MGB sportscar. In Oc<strong>to</strong><strong>be</strong>r 1962 the MGB Mk1 wasintroduced with a three main <strong>be</strong>aring engine, 18G; main <strong>be</strong>arings that were of a largerdiameter. The main <strong>be</strong>arings were 2.125" <strong>an</strong>d the big ends 1.875", both one eighth of <strong>an</strong>inch bigger th<strong>an</strong> the 1622cc engine, <strong>an</strong>d had copper/lead linings. The bores were of80.26mm <strong>an</strong>d the same stroke of 89mm, <strong>an</strong>d it produced 95bhp at 5400rpm, with110lbs/ft <strong>to</strong>rque at 3000rpm. To get the cylinders in, the block was again re-cored, <strong>an</strong>dthe cylinders siamesed so that no water could get <strong>be</strong>tween Nos. 1&2, or 3&4. Thedist<strong>an</strong>ce <strong>be</strong>tween those cylinders was tiny, <strong>an</strong>d a good quality head gasket is needed <strong>to</strong>seal the small ‘l<strong>an</strong>ds’. Again this new engine was first in <strong>an</strong> M.G., as a similar unit was<strong>to</strong> <strong>be</strong> fitted <strong>to</strong> the ADO17, Austin 1800 fwd saloon, itself delayed until Oc<strong>to</strong><strong>be</strong>r 1964.The engine had twin SU HS4 carburetters, with 8.8 <strong>to</strong> 1 compression ratio, <strong>an</strong>d the earlydiagonally split big end <strong>be</strong>arings. Valve sizes were 1.56" inlet <strong>an</strong>d 1.34" exhaust,camshaft valve timing was that of the MGA, 16;56;51;21 with .365" lift. Later the inletvalve size was enlarged in the 1971 18V engine, me<strong>an</strong>ing the side of the cylinder blockit lived above, had <strong>to</strong> <strong>be</strong> machined out a tiny bit <strong>to</strong> clear the valve head when it wasfully open. It had paper element air filters, one per carb, that also acted as air intakesilencers<strong>to</strong> improve the car’s image. By February 1964 the USA market had <strong>be</strong>gun <strong>to</strong>have its effect on the car, as a closed circuit breather system was fitted, using adiaphragm valve as in the ‘A’ series Midget, <strong>an</strong>d the engine <strong>be</strong>came a 18GA unit. Solidskirt pis<strong>to</strong>n were fitted. The tachometer was cable driven off the camshaft.1963 nearly saw a ‘Healey 1800’ version of the MGB. The idea fell on s<strong>to</strong>ney ground.Oc<strong>to</strong><strong>be</strong>r 1964 brought along the five main <strong>be</strong>aring 18GB engine, commonising itwith the Austin/Morris 1800 L<strong>an</strong>dcrab ADO17 model 18AMW engine, ( later 18H).The extra two main <strong>be</strong>arings needed a bigger oil pump, <strong>an</strong>d were 1 1/8" wide at front,centre <strong>an</strong>d rear, with the intermediates at 7/8" wide. The diameter was 2.125". Thisproduced a cr<strong>an</strong>kshaft with lots of overlap <strong>be</strong>tween journals <strong>an</strong>d counterweights, <strong>an</strong>dalmost unbreakable. For overseas markets a low compression version was available at8 <strong>to</strong> 1. In the five main <strong>be</strong>aring engines, the pinch bolt gudgeon pin was removed, <strong>an</strong>dpress-fit pins fitted, with horizontally split <strong>an</strong>d stronger big ends. The re-engineeringin<strong>to</strong> the extra <strong>be</strong>arings had produced a very heavy engine, <strong>an</strong>d could not have <strong>be</strong>eneasy. It weighs in at 520lbs with gearbox. An oil cooler <strong>be</strong>came st<strong>an</strong>dard equipment, agood use of the pipework the improved oil filter had generated back in 1956. Themech<strong>an</strong>ically driven tachometer off the camshaft was discontinued in 1964 on the1798cc block, ( along with the only other car <strong>to</strong> use this now on a ‘B’ series, the Riley 4/72 Farina in late 1966, ) <strong>an</strong>d <strong>an</strong> electronic impulse tacho was fitted. The M.G. Midgetwas also a recipient. The open cr<strong>an</strong>kcase vent had by now <strong>be</strong>come closed circuitbreathing.The ‘B’ series was a very old design by the mid-1960’s, it did date back <strong>to</strong> 1953!There had <strong>be</strong>en some two-litre ( 1994cc) ‘B’ series developed with a 83.24mm bore, for112

the MGB, but nothing came of them. In the early 1960’s BMC were looking at a 1500cc<strong>an</strong>d 2000cc V4 engine <strong>to</strong> replace the ageing ‘B’. They copied the L<strong>an</strong>cia narrow V4engine, building two 1500cc V4 <strong>an</strong>d three 2000cc V4 engines, putting the 1500cc onesin<strong>to</strong> Austin A40 Farinas, two 2000cc V4’s in<strong>to</strong> two Austin A60 Cambridge saloons, <strong>an</strong>done 2000cc V4 in<strong>to</strong> a MGA then <strong>an</strong> early MGB. Rumour has it the MGB <strong>to</strong>pped 120 mphon a road test. It is not recorded how the Farinas coped! The two litre 1994cc fourcylinder in-line ‘B’ however was not wasted, as much later the recored block with allcylinders siamesed went in<strong>to</strong> the ‘O’ series engine.MGB & MGB GT Mk2 <strong>Engine</strong> (1967-71)Oc<strong>to</strong><strong>be</strong>r 1967, The MGB Mk2 18GD & 18GG UK engines, <strong>an</strong>d USA spec 18GF, therear engine plate was ch<strong>an</strong>ged <strong>to</strong> fit a new stronger all synchromesh gearbox, or <strong>an</strong>au<strong>to</strong>matic gearbox. To take the larger diameter nose end of the first motion shaft, the‘spigot’ <strong>be</strong>aring in the flywheel end of the cr<strong>an</strong>kshaft was much larger. <strong>Engine</strong>s werenow not interch<strong>an</strong>geable with the smaller Farinas without a lot of machining! From1970 the modifications <strong>to</strong> the cylinderhead were bigger inlet valves, at 1.625" diameter,( 18GF units.) Ignition timings <strong>an</strong>d carb needles <strong>be</strong>come a nightmare from now on, usea workshop m<strong>an</strong>ual <strong>to</strong> sort them out. A Lucas 16AC (18GD,) or 16ACR, (18GG),alterna<strong>to</strong>r was fitted <strong>an</strong>d cars altered <strong>to</strong> negative earthing, <strong>to</strong> suit. The bolt holes in theblock for its bracket were already there, dating from 1966!Oc<strong>to</strong><strong>be</strong>r 1969 brought 18GHFederalised engines with exhaust emission control, <strong>an</strong>d this Americ<strong>an</strong> Cle<strong>an</strong> Air Lawwas <strong>to</strong> sap the MBG’s power as the years passed. ( Eventually the North Americ<strong>an</strong>California Spec cars only produced about 70bhp.)MGB & MGB GT Mk3 <strong>Engine</strong> (1971-80)Oc<strong>to</strong><strong>be</strong>r 1971, MGB Mk3, now with SU HIF4 carburetters, 18V engine, power down<strong>to</strong> 84bhp, 102 lb <strong>to</strong>rque for UK markets, <strong>an</strong>d 82bhp 97lb <strong>to</strong>rque for the USA. All USAcars now required pollution control systems. Twin SU HIF4 carburetters were nowfitted, similar <strong>to</strong> the Morris Marina 1800TC, <strong>an</strong>d the later M.G. Metro 1300 single unit.The 18V variations in ignition timing alone needs its own book. The USA market musthave taken up hours of the M.G. comp<strong>an</strong>ies time <strong>to</strong> keep up with legislation. The goodpoint on the 18V is the fitment of a throw-away oil filter c<strong>an</strong>ister, just spin on a new one,a ‘spin-off’ from the Marina 1800!! It is the 1798cc 18V cylinder block that has the cu<strong>to</strong>ut for the inlet valve clear<strong>an</strong>ce on each cylinder.1971 also saw <strong>an</strong>other car that was <strong>to</strong> use the MGB 1800 engine in 18V form, ( withsingle valve springs, not double as previously.) In April that year the Morris Marina1800TC was on sale, it lasted until April 1978, when the ‘O’ series ousted it, a ‘B’ serieswith a single ohc! The Marina 1800 sump has a half litre less oil capacity th<strong>an</strong> the MGB.At least the arrival of the Marina 1800 saloon me<strong>an</strong>t BMC would spend a few bob onsorting out the terribly worn out Tr<strong>an</strong>sfer Machines that turned out the ‘B’ series. Thepoor old ‘B’ series engine kept getting <strong>an</strong>other couple of years grace, but these oddyears were adding up <strong>to</strong> a very long production run. The 1800TC 1798cc Marinaengines were very similar <strong>to</strong> the MGB unit. It differed in its m<strong>an</strong>ufacture in that it useda flow-cast-iron cr<strong>an</strong>kshaft ( copying Fords system,) with the same five main <strong>be</strong>arings,<strong>an</strong>d a slightly different 12H4735 cylinderhead, the oil feed <strong>to</strong> the rear rocker wasmoved a little, needing a modified rocker pillar with <strong>an</strong> extra ‘foot’ on it, ( known as<strong>an</strong> offset feed.) Otherwise it was the same unit, <strong>an</strong>d gave the Marina quite good113

perform<strong>an</strong>ce (in a straight line). Half a million Marinas were made up <strong>to</strong> 1978, the carcarried on with the 1300 ‘A’ Plus series Ital <strong>an</strong>d 1700 ‘O’ series until 1981. Over1,500,000 Marinas were made in <strong>to</strong>tal. The ‘Marina’ 12H4735 cylinderhead eventuallyfed in<strong>to</strong> the MGB production line, in about mid-1975, commonising parts. It had <strong>be</strong>ttercooling with wider internal waterways (cores) <strong>an</strong>d all the 18V & 18H (fwd & rwd),engines had decent inlet valve stem seals, like little caps over the valve guide replacingthe ‘O’ rings. This <strong>be</strong>tter oil control was necessary <strong>be</strong>cause of catalytic converters, whodislike burnt oil. Pis<strong>to</strong>ns had their oil control rings improved for the same reason. TheMarina 1800TC even had the MGB impulse tachometer, but neither used a catalyst inUK or Europe<strong>an</strong> specification. The 1971 MGB had <strong>an</strong> air pump for the USA market, <strong>an</strong>dthe export 1800 “Austin” Marina underwent the same USA power sapping modifications.(Morris was <strong>an</strong> unknown name in the USA.)1973 saw a Federalised ohc ‘O’ series developed for the MGB, but the lack ofdecision over the TR7 soaked up funds, <strong>an</strong>d BL w<strong>an</strong>ted the MGB replaced <strong>an</strong>yway, sowhy invest in it? The ‘O’ Series went elsewhere.1975, Smaller inlet valves were again used ( from the Austin A60/Morris Oxfordseries six, 1.562" dia.) For the North Americ<strong>an</strong> market it was fitted with the singleZenith 175 CD5T (Strom<strong>be</strong>rg), carburetter with <strong>an</strong> au<strong>to</strong>matic choke, <strong>an</strong>d catalyticconverter. The USA had <strong>be</strong>en using leadfree fuel for some years, now it was m<strong>an</strong>da<strong>to</strong>ry.All USA spec MGB <strong>an</strong>d Marinas were now unleaded. These cars had electronicignition, in a Lucas 45DE4 distribu<strong>to</strong>r. The UK spec cars now had the 45D4 distribu<strong>to</strong>rwith a single piece ‘quick-fit’ points set <strong>an</strong>d no adjustment on the vacuum adv<strong>an</strong>ceunit. Those terrible carbon-string ignition leads were fitted.1976 saw the engine driven cooling f<strong>an</strong> on the water pump <strong>be</strong>ing replaced with athermostatically controlled plastic f<strong>an</strong>, two for USA cars. Oc<strong>to</strong><strong>be</strong>r 22nd 1980 saw thelast MGB, <strong>to</strong>tal production 512,880 cars.After the ‘B’ series engine got <strong>to</strong> the 18GH series, the second letter in the num<strong>be</strong>ring,(18GH-’U’,) was given more me<strong>an</strong>ing, As normally, the ‘U’ me<strong>an</strong>t central gearch<strong>an</strong>ge,then ‘RU’ me<strong>an</strong>t overdrive, ‘We’ all synchromesh gearbox, ‘RWe’ all synchro withoverdrive, ‘Rc’ au<strong>to</strong>matic gearbox. Once the st<strong>an</strong>dardised 18V unit came, in Oc<strong>to</strong><strong>be</strong>r1971, there followed a set of num<strong>be</strong>rs that indicated the market the car was me<strong>an</strong>t, forinst<strong>an</strong>ce in 1972 18V/582F was the UK; 18V/581Y Europe; <strong>an</strong>d 18V/672Z NorthAmerica. This system <strong>be</strong>came quite complex, see the list on MGB engines <strong>be</strong>low.If you have read so far, but only on the MGB, you will think it a bit slim. But the ‘B’series engine in the use of M.G. entails the whole chapter. By the time the MGB wasfitted with its first 1798cc engine in 1962, over two <strong>an</strong>d a quarter million engines in thisseries had already <strong>be</strong>en made, so it is acceptable <strong>to</strong> underst<strong>an</strong>d it was well sorted, <strong>an</strong>dwould need little modification. Only the North Americ<strong>an</strong> market caused it problems,here in the UK the car romped away as a success, but this is not about the evergreenMGB, but its engine. The engine feels almost unburstable, <strong>an</strong>d gives good perform<strong>an</strong>ce,<strong>an</strong>d is easy <strong>to</strong> tune, the tuning after-market is full of goodies. It is so reliable itwill run in <strong>an</strong> awfully neglected state, but will use oil <strong>an</strong>d drink petrol when welloverdue a reconditioning. If the servicing periods are kept <strong>to</strong>, <strong>an</strong>d using good qualityoil, it will run well past 100,000 miles, <strong>an</strong>d longer if pampered. Talking of neglect, theopposite is true of the lovely res<strong>to</strong>red cars seen at M.G. meetings, but one wonders atthe technical ability of the few who put the cooling f<strong>an</strong> on the wrong way round so itblows <strong>to</strong>wards the radia<strong>to</strong>r. I pointed this out <strong>to</strong> a lovely BRG pull-h<strong>an</strong>dle cars owner114

BMC ‘B’ SeriesThe tight MGA engine bay.The nice open MGB engine bay. This is a 18GB unit, the first five main <strong>be</strong>aring block.115

once, who had his immaculate engine on display with the bonnet open, <strong>an</strong>d he <strong>to</strong>oksome convincing! Faults other th<strong>an</strong> wear <strong>an</strong>d neglect, c<strong>an</strong> <strong>be</strong> in the vent pipe system.The USA market led <strong>to</strong> the engine having <strong>to</strong> ingest its own cr<strong>an</strong>kcase vent air <strong>an</strong>dfumes. Often plastic junctions <strong>an</strong>d rub<strong>be</strong>r hoses split after years in the heat of theengine compartment, giving weak mixtures, or oil consumption problems. The rub<strong>be</strong>rhoses of the ‘Closed Breathing System’ c<strong>an</strong> block up with solid carbon deposits,causing cr<strong>an</strong>kcase compression, oil leaks <strong>an</strong>d oil consumption. The main cause of thisis short journeys. Note that <strong>an</strong>y engine with a ‘Controlled Breathing’ system needs aspecial metered vent oil filler cap, which needs its filter cle<strong>an</strong>ing every 10,000 miles, orrenewing. The diaphragm inside the vent-valve fitted <strong>to</strong> some engines, on the inletm<strong>an</strong>ifold, c<strong>an</strong> split with age. If this splits oil consumption goes up, <strong>an</strong>d the engine runsroughly on a weak mixture. Later cars used a more sensible vent direct in<strong>to</strong> the body ofeach carb. It is easy <strong>to</strong> convert <strong>to</strong> leadfree, cylinderheads already modified are availableoff the specialists shelf on <strong>an</strong> exch<strong>an</strong>ge basis at competitive prices. A cross-flowcylinder head kit is available, in aluminium, putting the carbs over the distribu<strong>to</strong>r, forthe power freak.A OHC ‘B’ Series. The ‘O’ SeriesA short mention of <strong>an</strong> engine developed for, <strong>an</strong>d that nearly got <strong>to</strong> the MGB, is the<strong>be</strong>lt driven, single ohc development of the ‘B’ series, called the ‘O’ series. That just whatit was, a sohc ‘B’ Series, that produced less power that its former ohv unit, from 1700ccinitially, ( later 1994cc for the au<strong>to</strong>matic Marina.) It first saw use in 1978 in the fwdPrincess Mk2. Like the MGA Twin Cam it used the same ‘B’ series cylinder block, thistime a 18V version. The camshaft <strong>be</strong>came a jackshaft for the oil pump, <strong>an</strong>d thecr<strong>an</strong>kshaft nose carried a <strong>to</strong>othed <strong>be</strong>lt drive <strong>to</strong> the single ohc, running in a rib<strong>be</strong>daluminium cover. This cover had the mech<strong>an</strong>ical petrol pump on, <strong>an</strong>d the distribu<strong>to</strong>r inthe middle, facing <strong>to</strong> the offside. The petrol pump location <strong>be</strong>came a good area for oilleaks, keeping up a good old British tradition. The oil pump had eleven lo<strong>be</strong>s. It was a17V engine. Surprise, surprise, all dimensions <strong>be</strong>low the aluminium alloy cylinderhead are identical <strong>to</strong> the 1798cc MGB/Marina 1.8 engine, except the bore was 84.5mm<strong>an</strong>d the stroke 75.8mm in the 1700cc, <strong>an</strong>d 84.5mm bore with good old 89mm stroke inthe 1994cc version. It was ofcourse, the SAME block. Valve timings were 15;45;50;10 forthe 1700, <strong>an</strong>d 19;41;61;15 for the 2.0 litre, with .360" lift. With a single SU HIF6 it wasfitted <strong>to</strong> Morris Itals. It was re-developed in<strong>to</strong> the ‘E’ series, a four cylinder 17H, <strong>an</strong>d asix cylinder 23H engine. Not used as a rwd unit, with chain driven single ohv, SU HIF6carb, <strong>an</strong>d a 76.2mm bore with just 81.3mm stroke,..... but we are well out of ‘B’ seriesterri<strong>to</strong>ry here, though the late MGB’s nearly had the ‘O’ in Federalised state, butAbingdon was closed in 1980 just as two cars had <strong>be</strong>en fitted out <strong>an</strong>d road tested! ( SeeMontego/Maestro, Chapter 9.)Like the 2ltr V4 in 1964, the ‘O’ series MGB was never heard of again, except in afailed venture <strong>to</strong> build the MGB by As<strong>to</strong>n Martin of Newport Pagnell in 1980. The ‘O’<strong>an</strong>d ‘E’ series inward-vented via their flywheel housings, <strong>an</strong>d thence in<strong>to</strong> thecarburetters from the camshaft case. Both are full of metric threads <strong>an</strong>d bolt heads. Asix cylinder ‘E’ series MGB sounds nice though, with 2227cc, twin SU HIF6 carbs,125lb/ft <strong>to</strong>rque, 112bhp .....................The ‘E’ was fitted <strong>to</strong> the BL Maxi, Allegro, Maestro,<strong>an</strong>d six cylinder fwd Princess. The ‘E’ series led <strong>to</strong> the ‘R’ <strong>an</strong>d ‘S’ series of the M.G.Maestro, see later, as the ‘O’ series is <strong>to</strong> return in <strong>an</strong> M.G. The ‘O’ series was <strong>to</strong> have<strong>be</strong>en twin carburetted, or fuel injected, or turbo-charged, depending upon its market,in the MGB. A little of the ‘B’ series has lasted a lot longer, as the ‘O’ series was116

developed from it, going in<strong>to</strong> the later M.G. Maestro <strong>an</strong>d Montego in 1994cc form.From this ‘O’ engine was developed the ‘O2’ version, which with a shorter block <strong>an</strong>dother modifications was produced as the M16 engine that is used in the Rover 800series in the 1990’s. This eventually <strong>be</strong>came the ‘T’ series in the Rover 820.MGB ‘B’ Series <strong>Engine</strong>sPrefix Main Bearings Model Market Date if known18G Three Mk1, GHN3/D3 All Oct 1962/6418GA ,, Mk1, GHN3/D3 ,, April 1964/Oct 6418GB Five Mk1, GHN3/D3 ,, Oct 1964/6718GD ,, Mk2, GHN4/D4 UK/Europe Oct 1967/6918GF ,, Mk2, GHN4/D4 USA Oct 1967/6918GG ,, Mk2, GHN5/D5 UK/Europe Oct 1969/7118GH ,, Mk2, GHN5/D5 Europe Oct 1969/7018GJ ,, Mk2, GHN5/D5 USA Oct 1969/7018GK ,, Mk2, GHN5/D5 USA Oct 1970/7118V ,, Mk3, GHN5/D5 *** Oct 1971 onwards.***18V was followed by a code which indicates such things as exhaust emissioncontrol, evaporative loss control, etc, for the USA market; overdrive, carburettercr<strong>an</strong>kcase ventilation, etc for the UK <strong>an</strong>d Europe markets. If there is a ‘Y’ in the prefix,it is a Europe spec engine; if a ‘F’ a UK spec engine; if a ‘Z’ a North Americ<strong>an</strong> specengine, <strong>an</strong>d if <strong>an</strong> ‘AE’ ( after 1975) this indicates a catalytic converter, Californi<strong>an</strong> specengine. You need <strong>to</strong> see the workshop m<strong>an</strong>ual, as it gets very complex. Luckily, the UKspec hardly ch<strong>an</strong>ged from the 18GG, through the black painted 18V, <strong>to</strong> the end. 18Vengines have casting num<strong>be</strong>r 12H3503 on the block.MGB Cylinder Heads (UK Specifications only)1962 <strong>to</strong> 1970 part num<strong>be</strong>r 12H1326, 18G, 18GA,18GB,18GD, 18GG.all with double valve springs, <strong>an</strong>d inlet valve 1.562" dia.1970 <strong>to</strong> 1975 part num<strong>be</strong>r 12H2708, 18V 581, 582, 584, 779, 780.all with single valve springs, <strong>an</strong>d inlet valve 1.625" dia.Oct 1975 on part num<strong>be</strong>r 12H4735, 18V 846, 847, all with singlevalve springs, 1.562" inlet valve, <strong>an</strong>d offset oil feed hole <strong>to</strong> the rocker’s.117

Note that the BL 1800, from 1968 <strong>to</strong> 1975, used a 1.625" dia inlet valve, <strong>an</strong>d that itsequivalent 18H ( <strong>to</strong> the MGB/Marina 18V,) used double valve springs, <strong>an</strong>d is identical<strong>to</strong> that used on the MGB 1971 <strong>to</strong> 1974. The 12H1326 heads are prone <strong>to</strong> cracking<strong>be</strong>tween <strong>be</strong>tween ports, inspect carefully. The small inlet valve was re-introduced in1975 <strong>to</strong> make the engine comply with EEC 15 Exhaust Emission Regulations.The ‘B’ Series Limit!The dist<strong>an</strong>ce of the camshaft from the cr<strong>an</strong>kshaft limited the cr<strong>an</strong>kshafts throw,initially designed for just 1200cc <strong>an</strong>d 1489cc. This ‘throw’ was the now legendary’88.9mm’, ( or 89mm for short,) stroke. Look at the Triumph engine fitted <strong>to</strong> the laterMidget 1500, ( in the St<strong>an</strong>dard Eight drawing,) the dist<strong>an</strong>ce <strong>be</strong>tween camshaft <strong>an</strong>dcr<strong>an</strong>kshaft is much larger. Fitting pollution controls <strong>to</strong> the ‘B’ series for the North Americ<strong>an</strong>market seriously affected the MGB’s power output. The lowest state was the singleZenith fitted engine for California, where it was reduced from 95bhp <strong>to</strong> just 70bhp.Some other figures will show the s<strong>to</strong>ry, 1971 we still had 95bhp at 5,500rpm, with 105lbf <strong>to</strong>rque at 2500rpm. By 1973 bhp was 94; by 1974 it was 87, with 103lb <strong>to</strong>rque; by 1975it was 85 with 100lbf.Marina 1800TC & MGB 18V <strong>Engine</strong>sYou have a Marina engine you w<strong>an</strong>t <strong>to</strong> put in<strong>to</strong> your MGB? These two engines lookidentical, <strong>an</strong>d the actual castings virtually are. <strong>How</strong>ever, there were some differences,<strong>an</strong>d these were the flywheel & clutch, Triumph sourced items. Also the cr<strong>an</strong>kshaft was‘flow-cast’ <strong>an</strong>d not forged, on the Morris; the timing chain was single row, not doubleas on the MGB; the engine mountings were at the centre of the block each side, so thefront plate has no lugs for the MGB front mounts. The Marina drillings for themounting bolts break through in<strong>to</strong> the cr<strong>an</strong>kcase, so if the bolts are left out, you c<strong>an</strong>have a huge oil leak. The rear plate is very different, as the gearbox is the old three-railTriumph Herald unit, updated. The f<strong>an</strong> is a large multi-bladed plastic moulding on theMorris, not the three bladed steel one on the MGB. The cylinder head oil feed <strong>to</strong> therockers is mentioned later, but this necessitated a different piller for the rocker shaft.The sump pressing has two large lugs welded on, <strong>to</strong> brace the gearbox <strong>to</strong> the engine, onthe Morris, <strong>an</strong>d the sump capacity is a little less. Most of these differences c<strong>an</strong> <strong>be</strong> curedby bolting on MGB parts.<strong>Engine</strong> Mech<strong>an</strong>ic on ‘L’ PlatesAnother RAF s<strong>to</strong>ry, but this time in Germ<strong>an</strong>y. A fellow airm<strong>an</strong>, (<strong>an</strong> AvionicsTechnici<strong>an</strong>,) of some younger years th<strong>an</strong> I (<strong>an</strong> <strong>Engine</strong> Technici<strong>an</strong>), had purchased avery tidy MGB from a chap returning <strong>to</strong> the UK. This tidy white MGB had <strong>be</strong>en drivenhard, had <strong>be</strong>en through three owners at the same station from new, <strong>an</strong>d the enginerattled ominously. The fault was declared as worn main <strong>be</strong>arings, it was <strong>an</strong> early threemain <strong>be</strong>aring car, <strong>an</strong>d Europe has lots of nice fast au<strong>to</strong>bahns. To save trouble the ownerpurchased <strong>an</strong> exch<strong>an</strong>ge/reground cr<strong>an</strong>k from a BMC garage in Roermond, Holl<strong>an</strong>d.He had seen me tightening nuts <strong>an</strong>d bolts on engines, using my experience <strong>to</strong> judge<strong>to</strong>rque. He fitted his cr<strong>an</strong>kshaft, <strong>an</strong>d alas after a few weeks there was that terriblerumble again, with low oil pressure. When asked what <strong>to</strong>rque he pulled the caps up <strong>to</strong>,he said ”Torque, what´s that?“118

The ‘C’ series of 2693cc as fitted <strong>to</strong> a Riley 2.6, a car that upset the Riley traditionalists rather a lot, fitted as itwas with <strong>an</strong> Austin engine designed by Morris, <strong>an</strong>d on a chassis built for a Wolseley. It was not only M.G. whohad <strong>to</strong> use corporate parts, though M.G. made a much <strong>be</strong>tter job <strong>an</strong>d were successful.119

BMC ‘C’ series six cylinder engine, with its camshaft on the opposite side <strong>to</strong> the ‘A’ <strong>an</strong>d ‘B’ series. This was aMorris <strong>Engine</strong>s design with <strong>an</strong> integral inlet m<strong>an</strong>ifold cast in<strong>to</strong> the cylinderhead. The head studs even passedthrough the inlet ports! This is a 2912cc 1962 carburetter version.120

Chapter EightThose Other MGB’s ( <strong>an</strong>d MGF)MGC <strong>Engine</strong> (1967-69)The MGC has a special place in the post-BMC M.G. world, as it is a M.G. that usesa Morris engine, a tradition lost when BMC was born back in 1952. Whilst the ‘A’ <strong>an</strong>d‘B’ series engines are ADO designs, that of the ‘C’ series is that of Morris <strong>Engine</strong>s atCoventry. There are similarities <strong>to</strong> the other two, but the unit does follow old practice.The engine in the MGC is a redesign of the 2912cc six cylinder fitted in the <strong>to</strong>p of ther<strong>an</strong>ge luxury saloons of Austin , the A99 <strong>an</strong>d A110,<strong>an</strong>d Wolseley, the 6/99 <strong>an</strong>d 6/110.The 99 <strong>an</strong>d 110 refer <strong>to</strong> the bhp. To find its roots we need <strong>to</strong> go further back. The ‘C’ isnot a big ‘B’ series, that was the Blue Streak engine of BMC Australia, <strong>an</strong>d it was one ofthese that was used for measurements for the engine bay <strong>an</strong>d <strong>to</strong>rsion bar ifs layout inthe design stage. The ‘B’ <strong>an</strong>d ‘C’ camshafts are on opposite sides of the engine for astart.After the demise of the big Wolseley six cylinder ohc engines, <strong>an</strong>d the high camshaftfour cylinder 2.5ltr of Riley, in the BMC tidy up <strong>to</strong> sort out its m<strong>an</strong>y engines <strong>an</strong>dmultitude of bodies, a six cylinder in line ohv engine was born. It was completelytraditional, following the ‘A’ <strong>an</strong>d ‘B’ <strong>to</strong> <strong>be</strong> the third corporate engine in the family. Veryconservative in its design, it was for big saloon car use, dignity <strong>an</strong>d quality, <strong>an</strong>d <strong>be</strong>ttermade <strong>an</strong>d longer lasting th<strong>an</strong> the Vauxhall or Ford under-square sixes of the time.Being a Morris design, it was first fitted <strong>to</strong> the Morris Isis, (<strong>an</strong> Oxford with a longerbonnet,) <strong>an</strong>d then Wolseley 6/90 saloons for the 1954 London Mo<strong>to</strong>r Show, for deliveryin 1955. The engine was cast iron, with the inlet m<strong>an</strong>ifold cast integrally with thecylinderhead, which also had the head studs passing through, seen <strong>be</strong>fore on Morrisengines in the Wolseley 8hp 918cc ohv . The Morris had one SU H4 <strong>an</strong>d the Wolseleytwo SU H4, giving 85bhp at 4000rpm in the Morris <strong>an</strong>d 95bhp at 4500rpm in theWolseley. The bore <strong>an</strong>d stroke were 79.4mm <strong>an</strong>d 89mm. Notice the stroke was commonwith the ‘B’ series, as the engines were of a family group, this gave 2693cc. It had thediagonally split big ends like the ‘B’, <strong>an</strong>d pinch bolt gudgeon pins. Unlike the ‘B’ thecamshaft was on the other side of the engine, but it did use the same timing sprocketsas the ‘A’ <strong>an</strong>d ‘B’, in duplex chain form, <strong>an</strong>d the later ‘B’ Reynolds chain tensioner.Valve timings were conservative at 5;45;40;10, <strong>an</strong>d that inlet m<strong>an</strong>ifold did nothing forpower. An Austin was fitted with the same engine in late 1954, this having a singleZenith <strong>an</strong>d produced 85bhp like the Isis. The Wolseley <strong>be</strong>came very popular with PoliceForces, as it drove well, was fast, <strong>an</strong>d h<strong>an</strong>dled well, as did the Riley 2.6, thePathfinder replacement that was otherwise identical with the Wolseley, having lost itscontroversial coil sprung rear axle.In 1956 a tuned version of the A99 with twin Zenith carbs <strong>an</strong>d improvedm<strong>an</strong>ifolding, produced 105bhp at 4600rpm, it was called the A105, <strong>an</strong>d was also sold asa V<strong>an</strong>den Plas in low num<strong>be</strong>rs. Similar improvements were made <strong>to</strong> the A90 of 1956,with one carb, power up <strong>to</strong> 92bhp, ch<strong>an</strong>ging its name <strong>to</strong> the Austin A95 Westminster.The Morris Isis was a flop, as was the Riley 2.6, <strong>an</strong>d were both discontinued. TheWolseley <strong>an</strong>d Austin sold strongly.The engine was used in the Austin Healey 100-Six in 1956, with the 102bhp A105version <strong>an</strong>d twin SU H4 carbs of the Wolseley. Racing improves the breed, <strong>an</strong>d Healeyquickly fitted <strong>an</strong> improved cylinderhead <strong>an</strong>d proper inlet m<strong>an</strong>ifold, this increased121

power <strong>to</strong> 117bhp at 4750rpm at a stroke. In 1959 the engine was bored out <strong>to</strong> 2912cc,with a 88.3mm bore, <strong>an</strong>d the big Healey was shoved along by a massive 124bhp,<strong>to</strong>pping 114mph. In 1961 the engine was again improved with bigger valves <strong>an</strong>d powerwas up <strong>to</strong> 132bhp at 4750rpm with 117mph. The big six had not finished yet, as in 1963Healey extracted 150bhp from the engine, at 5250rpm, producing 121mph <strong>to</strong>p speed.Carburetters were now twin SU HS6 1 3/4". The Healey 3000 Mk3 was nearly a Healey4 litre GT, as it was <strong>to</strong> have the aluminium Rolls Royce industrial B60 engine, thateventually went in<strong>to</strong> the V<strong>an</strong>den Plas Princess 4litre ‘R’ saloon instead. Instead the 3000Mk3 kept the ‘C’ series, with even more bhp.So there was a precedent <strong>to</strong> use the BMC six cylinder in a sports car, <strong>an</strong>d some thinkthat was what the MGC was <strong>to</strong> <strong>be</strong>, a Healey 3000 replacement. The following showsthe use of the BMC six cylinder engine, more th<strong>an</strong> you might have suspected at first:-Model cc Prefix Power .Austin A90 2693 4 main <strong>be</strong>arings 26 85bhpMorris Isis 2693 26M 85Wolseley 6/90 2693 26W 95Riley 2.6 2693 26R 95Austin A105 2693 26 102Austin A105 V<strong>an</strong>den Plas 2693 26V 102Austin A95 Westminster 2693 26 92Austin Healey 100-Six 2693 26AH 102Austin Healey 3000 Mk1 2912 29AH 124Austin Healey 3000 Mk2 2912 29AH 132Austin Healey 3000 Mk3 2912 29AH 150Austin A99 Westminster 2912 29 103Wolseley 6/99 2912 29W 103V<strong>an</strong>den Plas Princess Mk1 2912 29V 103Austin A120 Westminster 2912 29A 120Wolseley 6/110 Mk1 & 2, 2912 29WA 120V<strong>an</strong>den Plas Princess Mk2 2912 29VA 120Austin Three Litre 2912 7 main <strong>be</strong>aring 29V 145M.G. MGC 2912 .. 29G 145BMC Reconditioned unit68GIn 1959 the Wolseley 6/99 had the bigger Healey ‘C’ series engine of 2912cc, with itstwin carbs, with 103bhp at 4750rpm. 1959 was also the year BMC went ‘Farina’ instyles.The same engine was fitted <strong>to</strong> the Austin A99 Westminster, now with twin SUcarbs, as Austins had dumped the Zeniths. A V<strong>an</strong>den Plas version, with its own grill<strong>an</strong>d trim, now appeared, later <strong>to</strong> gain a Rolls Royce four litre B60 aluminium version of<strong>an</strong> industrial engine, NOT the ‘RR’ car engine, <strong>an</strong>other BMC disaster. A really heftycr<strong>an</strong>kshaft underpinned this ‘C’ series engine, counterbal<strong>an</strong>ced, with main <strong>be</strong>arings of2.375" <strong>an</strong>d big end journals of 2". There were only four main <strong>be</strong>arings, but ample. The<strong>be</strong>tter camshaft of the Healey was fitted <strong>to</strong> the 1961 cars, now a Austin A110, Wolseley6/110 <strong>an</strong>d V<strong>an</strong>den Plas Mk2, though they never gained the Healey’s <strong>be</strong>ttercylinderhead <strong>an</strong>d inlet m<strong>an</strong>ifold, using that cast in<strong>to</strong> the head <strong>to</strong> the end. The camshafttiming was 5;45;51;21, that of the MGA <strong>an</strong>d MGB, but with a lower .314" lift. Powerleaped <strong>to</strong> 120bhp at 4750rpm. Inlet valves were now 1.69" diameter, <strong>an</strong>d exhaust 1.42".A large 10" dry clutch <strong>to</strong>ok the drive, though <strong>an</strong> au<strong>to</strong>matic gearbox was on offer.122

1959 also saw the development of a six cylinder from the 1489cc ‘B’ series, that wasnot continued, but did live on <strong>to</strong> <strong>be</strong> used based on the 1622cc ‘B’ series, for BMCAustralia. This engine is not a ‘C’ series, <strong>an</strong>d only built down-under as the Blue StreakSix.Like the ‘B’ series, the engine was destined for further use, as BMC sought <strong>to</strong>improve their FWD r<strong>an</strong>ge, except that the biggest car was not fwd, but the ‘Austin 3Litre’ that looked like a big ADO17 1800. The ‘C’ series was <strong>to</strong> <strong>be</strong> updated like the 5main <strong>be</strong>aring 18GB MGB 1798cc engine had <strong>be</strong>en, <strong>to</strong> have a main <strong>be</strong>aring each side ofeach cylinder giving seven, for extra smoothness. The poor old Austin 3 Litre lost out <strong>to</strong>the cash problems of the comp<strong>an</strong>y, <strong>an</strong>d flopped terribly. But that engine could <strong>be</strong> usedin a replacement for the defunct Austin Healey 3000, <strong>an</strong> old design dating back <strong>to</strong> theAustin Atl<strong>an</strong>tic, the Healey contract soon <strong>to</strong> finish. What <strong>be</strong>tter th<strong>an</strong> <strong>to</strong> fit it <strong>to</strong> amodified MGB, <strong>an</strong>d badge it as a Healey?July 1967 saw a six cylinder MGB, now called a MGC, for sale. It had the redesignedseven main <strong>be</strong>aring BMC ‘C’ series six cylinder engine me<strong>an</strong>t for the 3 ltr. It produced145bhp at 5250rpm, similar <strong>to</strong> the last Healey 3000 Mk3 though 5bhp less, with 170lb/ft <strong>to</strong>rque at 3400rpm, with its 2912cc engine of 83.3mm bore <strong>an</strong>d famous 89mm stroke.The compression ratio was 9 <strong>to</strong> 1, with twin SU HS6 1 3/4" carburetters with paperelement air filters in <strong>an</strong> air intake silencer. The camshaft timing was that of the last 4main <strong>be</strong>aring engines, 5;45;51;21 as were valve sizes. One wonders how BMC lost 5 bhpfrom that Healey engine, but they did it as well with the ZB Magnettes 68bhp in 1958 <strong>to</strong>the 66bhp of the Mk3 Magnette in 1959, <strong>an</strong>d that was the SAME engine. High oilconsumption c<strong>an</strong> <strong>be</strong> down <strong>to</strong> the inlet valve seals, <strong>an</strong> early ‘B’ series problem as well.Using the 1800 inlet valve cap-seals c<strong>an</strong> cure the problem of oil <strong>be</strong>ing sucked down thevalve guide in<strong>to</strong> the inlet m<strong>an</strong>ifold. The engine had <strong>an</strong> oil cooler as a st<strong>an</strong>dard fitting.It was a nice ‘lazy six’, but road testers complained it lacked mid-r<strong>an</strong>ge <strong>to</strong>rque, poorcamshaft timing perhaps? Septem<strong>be</strong>r 1969 saw the last MGC after a production run of8,999 cars.Because of the new six cylinder engines poor perform<strong>an</strong>ce, M.G. did consider usingthe Rolls Royce B6 industrial unit from the big Westminster based Princess ‘R’. TheMGC’s new engine simply was not designed for a sportscar, <strong>an</strong>d its seven main <strong>be</strong>aringcr<strong>an</strong>kcase was very massive, <strong>an</strong>d of cast iron. To use the 2433cc Blue Streak Australi<strong>an</strong>engine would have me<strong>an</strong>t this was unique <strong>to</strong> M.G. in the UK, so the comp<strong>an</strong>y wasforced <strong>to</strong> use the BMC Austin Three Litre component. Alas, the Blue Streak in theFarinas for the Australi<strong>an</strong> market did not sell very well either, <strong>an</strong>d were soon dropped.This 2433cc engine only produced 80bhp with its single SU carburetter.The power output could <strong>be</strong> improved with attention by Down<strong>to</strong>n Tuning, who soldthree stages of improvement, a mild stage two <strong>to</strong> 149bhp at 5,500 rpm, with stage three<strong>an</strong>d three SU carbs giving 174bhp at 5,500 rpm. The much later Rover V8 engine in theMGB GT V8 of 1973 produced 137bhp with 193lbs <strong>to</strong>rque, from a massive 3528cc. Incomparison that MGC engine was not <strong>to</strong>o bad , it just did not like revving. TA MPJMengine, <strong>an</strong>d Midget 1500 engine trouble again? Perform<strong>an</strong>ce of 120mph <strong>an</strong>d 0 <strong>to</strong> 60 in10 seconds is still good <strong>to</strong>day. Has <strong>an</strong>yone ever tried a M.G. Metro Turbo 1300 upagainst a MGC on a race track?123

The Rover/Buick 251 cu. in. aluminium alloy V8 engine, in its Rover environment of the P6B. Picture courtesyof Mo<strong>to</strong>r magazine . The SU carburetters in the MGC installation were at the rear, on a new m<strong>an</strong>ifold, <strong>to</strong> keepthe MGB bonnet line. In the M.G. it was detuned from 10.5 compression radio <strong>to</strong> 8.25 <strong>to</strong> 1.124

V8 PowerThe MG fac<strong>to</strong>ry version of the Rover V8 in <strong>an</strong> MGB, with aftermarket filters.A Rover SDI V8 shoehorned in<strong>to</strong> a 1800 MGB, very neatly done.125

Oddball MG enginesA V8 in a kit car based on MGB running gear.A MG YB saloon using a Morris Marina 1275cc ‘A’ series!126

Rover <strong>Engine</strong>s in M.G.sMGB GT V8 <strong>Engine</strong> (1973-76)The MGB GT V8, the longest title yet on <strong>an</strong> M.G, has a fascinating engine. The s<strong>to</strong>ryis that...Once up on a time the m<strong>an</strong>aging direc<strong>to</strong>r of Rover Cars Ltd. went over <strong>to</strong> the USA <strong>to</strong>try <strong>to</strong> sell his comp<strong>an</strong>y’s wares <strong>to</strong> the Americ<strong>an</strong>s. On visiting Mercury Marine whomake power boats, in 1964, he saw a second h<strong>an</strong>d aluminium 90 degree V8 enginesitting on the floor. Mercury were <strong>to</strong> trial fit it in<strong>to</strong> a boat. William Martin-Hurst, them<strong>an</strong>aging direc<strong>to</strong>r from Rover, asked about it, as it looked very small for <strong>an</strong> Americ<strong>an</strong>au<strong>to</strong>mobile engine. This particular unit had <strong>be</strong>en taken out of a scrap Buick Skylark car,it was of 215 cu.inch, <strong>an</strong>d had <strong>be</strong>en designed in the early 1950’s for the ‘compact’market. In 1952 it was up <strong>an</strong>d running, <strong>an</strong>d by 1960 in full production, <strong>an</strong>d was a copyof a post war BMW V8. But like BMC the huge comp<strong>an</strong>y of General Mo<strong>to</strong>rs, ( GM,)were commonising their engines, <strong>an</strong>d the expensive alloy V8 was dropped in 1964 after750,000 had <strong>be</strong>en made. The engine was out of production. A cast iron V8 had taken itsplace, everyone copying Fords system of ‘thin-wall’ casting, <strong>an</strong>d grey cast iron is halfthe price of cast aluminium, <strong>an</strong>d does not need cylinder liners. Martin-Hurst contactedGM <strong>an</strong>d offered <strong>to</strong> buy the m<strong>an</strong>ufacturing rights. GM thought he was joking <strong>an</strong>dignored him.But, he did take that engine off the garage floor back <strong>to</strong> Blighty, <strong>an</strong>d had itfitted in<strong>to</strong> a Rover 2000. Martin-Hurst then drove this car <strong>to</strong> London, <strong>an</strong>d picked upSpencer Wilks, a retired M<strong>an</strong>aging Direc<strong>to</strong>r of Rover Ltd. ( The Wilks Brothers WERERover.) This was in early 1965. Wilks could not <strong>be</strong>lieve how this Rover could go, <strong>an</strong>ddem<strong>an</strong>ded <strong>to</strong> see under the bonnet. Rovers were traditionally rather staid, solid, goodquality, long lived, saloon type mo<strong>to</strong>r cars, hence the nickname ‘Aunties’. Things<strong>be</strong>g<strong>an</strong> <strong>to</strong> move faster after that. Rover contacted GM again, who <strong>to</strong>ok up their offer,sending over the drawings, the designer of the V8, one Joe Turley, for 18 months, <strong>an</strong>d 39completed engines. Rovers old inlet-over-exhaust (ioe,) engines were very old, <strong>an</strong>dneeded replacing. The Rover 2000 sohc had <strong>be</strong>en introduced, but the bigger P6 ThreeLitre saloons needed <strong>an</strong> update as well. This car gained its V8 in 1967, <strong>be</strong>ing the P5B,<strong>an</strong>d then the Rover 2000 was so fitted in 1968, <strong>be</strong>ing the P6B, ( ‘B’ is for Buick.)The P5B was much improved, as its old 2995cc six cylinder engine only did15.6mpg, where as this new <strong>to</strong> Rover 3528cc V8 did 19.2mpg in the massive body.Rover produced the engine in a slightly different way <strong>to</strong> GM, in that Rover s<strong>an</strong>d castthe cylinder block, machined it <strong>an</strong>d press fitted the cast iron cylinder liners. Thecylinder head was a gravity die casting, <strong>an</strong>d sumps <strong>an</strong>d covers were pressure die cast,all by Birmingham Aluminium Comp<strong>an</strong>y. In this USA spec. it carried a high 10.5 <strong>to</strong> 1compression ratio, requiring 5 star petrol, turned out 184 bhp at 5200rpm, <strong>an</strong>d couldpush the P6B up <strong>to</strong> 125mph with the later m<strong>an</strong>ual gearbox, <strong>an</strong>d do 24mpg normaldriving. Initially the engine was fitted <strong>to</strong> a Borg Warner strengthened Type 35au<strong>to</strong>matic gearbox, no m<strong>an</strong>ual gearbox <strong>be</strong>ing available <strong>to</strong> take the huge <strong>to</strong>rque itproduced, of 215 lb/ft. A reinforced Rover 2000 gearbox with taper roller <strong>be</strong>arings, newcasing, <strong>an</strong>d with its own oil pump, eventually arrived in 1971.The Morg<strong>an</strong> Comp<strong>an</strong>y of Malvern Link, Worcestershire, were the first sports carfirm <strong>to</strong> fit this engine in 1968, called the Morg<strong>an</strong> Plus 8, it had neck jarring accelerationif you were not careful. With the successful P5B <strong>an</strong>d P6B there followed the R<strong>an</strong>geRover in 1970 <strong>an</strong>d a L<strong>an</strong>d Rover Series 3 version in 1971, both using a low compression8.25 <strong>to</strong> 1, 140bhp engine. The Rover SD1 had the engine at its launch in 1976, ( the sameyear the millionth L<strong>an</strong>d Rover came off the lines.) Rover had produced 90,000 V8127

engines by 1980! Alas it was not until the late 1980’s the steel inserts <strong>to</strong> the combustioncham<strong>be</strong>r was modified <strong>to</strong> take lead-free petrol, Rover do not recommend leadfree fuelfor the early engines, ( though experience says they c<strong>an</strong> withst<strong>an</strong>d leadfree fuel!!) In1998 a 4 litre version is still in production with L<strong>an</strong>d Rover, who <strong>to</strong> complete the circle,now <strong>be</strong>long <strong>to</strong> BMW. The 1966-67 3-litre engine fitted <strong>to</strong> the Brabhams Formula 1winner, used the Buick V8 block.As Rover, Leyl<strong>an</strong>d, <strong>an</strong>d Austin Morris had all merged by the 1970’s, this enginecame within the remit of M.G. Ken Costello, had shown BL how <strong>to</strong> get a V8 Rover in<strong>to</strong>a MGB, <strong>an</strong>d he was doing well. So in April 1973 M.G. pushed their very own V8version off the production line. The all aluminium alloy V8 engine has a bore of 89mm<strong>an</strong>d a stroke of 71mm, giving 3532cc, there were push rod ohv with self adjustinghydraulic cam followers. The camshaft valve timings were 30;75;68;37 with .390" lift. Agear type oil pump moved the oil about at a disconcertingly low pressure for M.G.enthusiast, 30 <strong>to</strong> 40psi <strong>be</strong>ing good. Most other M.G. engines use 50 <strong>to</strong> 75psi, butAmeric<strong>an</strong>s go for a good flow in wide oil galleries, as opposed <strong>to</strong> high pressures. Likethe 1798cc ‘B’ <strong>an</strong>d 1275cc ‘A’, the gudgeon pins were a press fit in<strong>to</strong> the connecting rodlittle end. The short, very s<strong>to</strong>ut cr<strong>an</strong>kshaft had wide big ends of 2" diameter, <strong>an</strong>d fivewide main <strong>be</strong>arings of 2.29" diameter. All <strong>be</strong>arings were steel back shell <strong>be</strong>arings withlead-indium alloy lining.The 90 degree V8 fitted <strong>to</strong> the MGB <strong>an</strong>d GT body was thelower powered unit from the R<strong>an</strong>ge Rover/L<strong>an</strong>d Rover, so it had a 8.25 <strong>to</strong> 1compression ratio, giving 137bhp at 5000 rpm <strong>an</strong>d 193 lb/ft <strong>to</strong>rque. A special inletm<strong>an</strong>ifold that <strong>to</strong>ok the two SU HIF6 1 3/4" carburetters <strong>to</strong> the rear of the engine wasfitted, <strong>to</strong> clear the bonnet, <strong>an</strong>d two large frying-p<strong>an</strong> paper air filter elements finish thejob. The lazy V8 allowed the MGB GT V8 <strong>to</strong> idle along at just 23.4 mph per 1000rpm,<strong>an</strong>d 28.5 mph in overdrive. Maximum speed even with low compression, was 124mph,<strong>an</strong>d <strong>to</strong> 60 was in 8.6 second. It did 24 mpg! The V8 was virtually the same weight as therather corpulent 1798cc cast iron ‘B’ series. British Leyl<strong>an</strong>d were never lucky with goodcars, as by Septem<strong>be</strong>r 1976, production was s<strong>to</strong>pped <strong>to</strong> promote a competi<strong>to</strong>r, the TriumphStag, cast iron V8, sports car disaster, after just 2591 cars.Again, having experience of this engine, it does not take kindly <strong>to</strong> short coldjourneys. The oil has large areas of cold aluminium surface <strong>to</strong> flow over, <strong>an</strong>d generatesa lot of sludge if not boiled off on a good fast 25 mile run often. This off-white sludgecalled mayonnaise, ( oil mixed with water, ) plays havoc with the hydraulic camfollowers, causes internal corrosion, <strong>an</strong>d blocks oil ways. Later Rover SD1 engines hadsolid followers, which also permit higher rpm as hydraulic follower’s oil c<strong>an</strong> foam ifover-revved. Camshafts, the most highly stressed bit of <strong>an</strong>y engine, suffer badly, oftenlo<strong>be</strong>s <strong>be</strong>ing ground off <strong>to</strong> just a little bump. The camshaft is case-hardend, a thin hardsurface on a softer steel centre. This is quite a strong structure, but once you wear offthe few thous<strong>an</strong>dths of <strong>an</strong> inch of hard surface, they wear rapidly. Use it often, ch<strong>an</strong>gethe oil often, ch<strong>an</strong>ge the filter often, in fact service it often <strong>an</strong>d it will last forever.M.G. RV8 <strong>Engine</strong>The M.G. RV8 used a similar V8 unit, but of 3950cc with a 94mm bore, 71mm stroke,<strong>an</strong>d 9.35 <strong>to</strong> 1 compression ratio, producing 190ps ( 184bhp,) at 4750rpm, with <strong>to</strong>rque of318nm ( New<strong>to</strong>n/Meters,) giving 0 <strong>to</strong> 60 in 6 seconds <strong>an</strong>d 135mph. It has electronicignition <strong>an</strong>d a ECU engine m<strong>an</strong>agement system with multi-point fuel injection, <strong>an</strong>dwas from the <strong>to</strong>p of the r<strong>an</strong>ge ‘R<strong>an</strong>ge-Rover 4.0i V8’. It was a limited productionvehicle of 2000. Sometimes I wonder if things are leaving me <strong>be</strong>hind, what is a ps?128

The Rover K16 <strong>to</strong>hc engine as used in the MGF. Cylinder head of the 1.8i shown <strong>be</strong>low, <strong>an</strong>d the oil systemoverleaf.Copyright Haynes M<strong>an</strong>uals.129

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The Buick 215 cu.in. engine was often bored out <strong>to</strong> 4400cc in the USA forcompetition use, <strong>an</strong>d tuned <strong>to</strong> give 350bhp.Use of the Rover/Buick V8Model from - <strong>to</strong> .750,000GM Buick Skylark Compact 1960-1964GM Buick Special 1960-1964GM Pontiac Tempest 1960-1964GM Oldsmobile F85 Cutlass 1960-1964 }Rover P5B 3 1/2 Litre saloon 1967-1973Rover P6B 3500/3500S saloon 1968-1975R<strong>an</strong>ge Rover 4wd off-road 1970- 1993R<strong>an</strong>ge Rover 4.0i V81994-<strong>to</strong> dateL<strong>an</strong>drover 4wd Discovery 1980-1993L<strong>an</strong>drover Discovery V8i1993-<strong>to</strong> dateRover SD1 3500 1977-1982Rover SD1 3.5 V<strong>an</strong>den Plas 1980-1986Rover SD1 Vitesse 1982-1986Series 3 L<strong>an</strong>drover & vari<strong>an</strong>ts 1971-<strong>to</strong> date101 inch Forward Control Rover 1975-1977LDV Sherpa1990- <strong>to</strong> dateMorg<strong>an</strong> Plus 8 1968-1980Triumph TR8 1980-1981MGB GT V8 1973-1976MG RV8 1992-1996madeM<strong>an</strong>y were used in specialist cars like TVR, Westfield, Marcos, Lister & Ginetta.MODERN M.G. SportscarsM.G. MGF 1.8i, <strong>an</strong>d VVC <strong>Engine</strong> (1995- still in production in 1998)The Rover four cylinder ‘K’ series was first used in 1990. It was fitted in the fwdRover 100 (Metro) sohc 1.1litre ‘111’, <strong>an</strong>d 1.4litre (1396cc) ‘114’; <strong>an</strong>d the sohc 1.4 litre‘214’. By 1995/6 it had <strong>be</strong>come the main engine of the comp<strong>an</strong>y, <strong>an</strong>d included the dohc1.8 litre (1796cc) ‘218 VVC’ <strong>an</strong>d ‘218 TD’ <strong>to</strong>urer; <strong>an</strong>d dohc ‘618i’ <strong>an</strong>d ‘618Si’ r<strong>an</strong>ges, allwith a <strong>be</strong>lt driven camshafts. For the 1.8 litre MGF it has a <strong>to</strong>othed <strong>be</strong>lt drive dohc withsixteen valves, new connecting rods <strong>an</strong>d cr<strong>an</strong>kshaft, with lightweight pis<strong>to</strong>ns, with acast aluminium sump, with the VVC model having a special inlet m<strong>an</strong>ifold. It wasdesigned as a very efficient saloon car engine, <strong>to</strong> take Rover in<strong>to</strong> the next millennium,<strong>an</strong>d is no relation <strong>to</strong> the fwd units of BMC/BL, or Honda. This is no engine for thetinkering enthusiast, <strong>an</strong>d heralds a new type of M.G. owner, one with cle<strong>an</strong> h<strong>an</strong>ds!This two seater sports car, with its mid engine-configuration has the Rover ‘K16’series all aluminium engine fitted, of 1796cc, 89mm bore, 80mm stroke,<strong>an</strong>d fourcylinders, with double overhead camshafts, (dohc), <strong>an</strong>d four valves per cylinder, twoinlet <strong>an</strong>d two exhaust. All engine functions are controlled electronically via a Rover/Mo<strong>to</strong>rola Modular <strong>Engine</strong> M<strong>an</strong>agement System, (MEMS). This was the first model <strong>to</strong>get the 1.8 litre, 120ps (118bhp), at 5500rpm, version of this engine, which is well131

hidden from view. It is available in two power options; as above, or with the sameengine but with a variable valve control, that hydraulically & mech<strong>an</strong>ically alters thecamshafts inlet valve timings, termed the 1.8i VVC, 145ps ( 143bhp,) at 7000rpm.Thecamshaft timing is carried out by slowing down or speeding up the lo<strong>be</strong>’s travel acrossthe valve bucket (cam follower), so keeping the valve open for a shorter or longerperiod, depending what is dem<strong>an</strong>ded of the engine, ie under acceleration, valves openlonger for more power; cruising, open less for economy. The control unit is in thecylinderhead. At 4500rpm the 1.8i engine produces 165nm <strong>to</strong>rque, 0 <strong>to</strong> 60mph in 8.5seconds; <strong>an</strong>d the 1.8i VVC 174nm, 0 <strong>to</strong> 60 in 7 seconds. They both have three-way,closed loop catalytic converters, with the exhaust gasses moni<strong>to</strong>red by <strong>an</strong> oxygensensor, (Lambda,) so c<strong>an</strong> only run on leadfree petrol, <strong>an</strong>d spark plugs are said <strong>to</strong> last60,000 miles. The five speed gearbox is related <strong>to</strong> the Rover 200 <strong>an</strong>d 400.The all alloy engine has 4 replaceable steel, wet cylinder liners, in direct contactwith the cool<strong>an</strong>t. The K8 version in the saloon cars indicates just 8 valves, the term K16indicates 16 valves. The construction consists of three major castings, the cylinderhead, cylinder block, <strong>an</strong>d cr<strong>an</strong>kshaft main <strong>be</strong>aring ladder. The head comes with acamshaft carrier. All of it is tied <strong>to</strong>gether by ten long through bolts, which fulfil the taskof main <strong>be</strong>aring <strong>an</strong>d cylinder head fastening. Ten smaller bolts hold the block <strong>to</strong> thecr<strong>an</strong>kcase, so the head c<strong>an</strong> <strong>be</strong> removed separately. The long bolt holes in the engine actas breather <strong>an</strong>d oil return passages. There are five main <strong>be</strong>arings. Hydraulic tappets areused under the two camshafts.It must <strong>be</strong> difficult <strong>to</strong> open the bonnet <strong>an</strong>d show off a cle<strong>an</strong> tidy MGF engine! In1998 MG intend <strong>to</strong> run EX255, a very special MGF derivative, <strong>to</strong> regain the l<strong>an</strong>d speedrecord for that class of car, on Bonneville salt flats, USA. This ‘MGF’ has a 4.8 litre MG/Rover V8 of 94mm bore <strong>an</strong>d 86.4mm stroke, producing 900bhp at 8000rpm, <strong>an</strong>d <strong>to</strong>rqueof 590lbs.ft. With a reinforced V8 block, 2.1" dia big ends, 2.25" dia main <strong>be</strong>arings, inletvalves of 1.9" dia <strong>an</strong>d exhaust valves of 1.6" dia, self learning fuel injection systemfeeding in<strong>to</strong> twin superchargers, a dry sump lubrication system, <strong>an</strong>d a 150 litre coolingsystem with no radia<strong>to</strong>r. All in a much modified MGF frame, it hopes <strong>to</strong> <strong>be</strong> the fastestMG ever, 300mph plus.V8 Oil WorryHaving just spent a small fortune on rebuilding a V8 engine, upon turning over themassive power unit, the oil gauge failed <strong>to</strong> register <strong>an</strong>ything. P<strong>an</strong>ic!! Checking the dipstick <strong>to</strong> see if I had put <strong>an</strong>y oil in showed a nice green level of Duckhams <strong>be</strong>st 20/50. Idare not run the engine again, so decided <strong>to</strong> check the oil pump. It had oil in it, but notthe huge dollop one would expect had it <strong>be</strong>en pumping oil. I never run <strong>an</strong> engine untilI KNOW the oil is circulating, <strong>an</strong>d have almost wound my arm off on ‘B’ series, using astarting h<strong>an</strong>dle <strong>be</strong>fore now. A check with the m<strong>an</strong>ual mentioned filling the oil pumpwith Vaseline, <strong>an</strong> old trick I had forgotten, I had done this m<strong>an</strong>y years <strong>be</strong>fore on aircraftengines <strong>to</strong> get the pump <strong>to</strong> ‘lift’. One tin of Vasaline later, <strong>an</strong>d the oil flowed <strong>be</strong>autifully.I fitted the ro<strong>to</strong>r, <strong>an</strong>d fired her up, <strong>an</strong>d oil pressure needle moved round the gauge,much <strong>to</strong> my relief. I always assemble <strong>an</strong> engine using STP, as it remains in the <strong>be</strong>aringson start-up.Simply carrying out <strong>an</strong> oil <strong>an</strong>d filter ch<strong>an</strong>ge c<strong>an</strong> drain <strong>an</strong> oil pump, which is whysome, like early XPAG engines, have priming plugs. The Midget 1500 engine, <strong>an</strong>dthose ‘B’ series with upright c<strong>an</strong>ister filters, must have <strong>an</strong> oil filter with a <strong>an</strong>ti-draindown valve in it, or the engine c<strong>an</strong> start up every time with <strong>an</strong> empty oil pump. Early132

A sketch of the ‘E’ series engine that was developed in<strong>to</strong> the ‘R’ <strong>an</strong>d ‘S’ series in the modern fwd saloons, here infour cylinder 1700cc, five speed Maxi form. It could <strong>be</strong> extended <strong>to</strong> a 2227cc six cylinder, but fr<strong>an</strong>kly the’O’series was a <strong>be</strong>tter engine.133

BL ‘R’ & ’S’ SeriesThe MG Montego <strong>an</strong>d MG Maestro have a following, <strong>an</strong>d with a turbo fitted are a very fast MG indeed.134

Modern MG SaloonsTurbo charged MG Maestro engine bay , using th e’O’ series.Turbo charged MG Metro engine, using the 1275cc ‘A’ series.135

The fuel m<strong>an</strong>agement system of the MG Montego <strong>an</strong>d Maestro, Lucas injection.136

Heralds <strong>an</strong>d Spitfires developed noticeable big-end rattle <strong>be</strong>cause owners fitted <strong>an</strong>ycheap old filter, <strong>an</strong>y engine is at its most vulnerable starting cold.Theres nothing like ‘no-oil-pressure’ <strong>to</strong> give <strong>an</strong>yone a heart failure, the only otherinst<strong>an</strong>ce I c<strong>an</strong> compare it with is shoving on the brake pedal <strong>to</strong> find theres a fluidleak...<strong>an</strong>d it goes <strong>to</strong> the floor!Leaded or Unleaded?Since about 1984, all Rover V8 engines have hardend steel exhaust valve seats, soc<strong>an</strong> run on unleaded petrol. The earlier cars use steel inserts for all the valve seats, asthe engine is <strong>an</strong> aluminium alloy casting, but these are not guar<strong>an</strong>teed <strong>to</strong> cope withunleaded fuel. The L<strong>an</strong>drover model is exported all over the world, so it was <strong>an</strong>obvious move <strong>to</strong> update the engine <strong>to</strong> use a fuel now m<strong>an</strong>da<strong>to</strong>ry in m<strong>an</strong>y countries.Such later cylinder heads should fit the earlier M.G. engines for <strong>an</strong> easy conversion.The RV8 <strong>an</strong>d MGF are modern unleaded engines, with catalytic converters, <strong>an</strong>dmust NOT use leaded fuel as this destroys the catalytic lining in the unit. It is alsoimport<strong>an</strong>t not <strong>to</strong> park one of these models at a meeting/rally, over dry grass, after along run. The heat off the cat’ will set fire <strong>to</strong> the grass, not a very smart party trick.137

Chapter Nine1980 <strong>to</strong> 1990 B/L & Austin RoverFour Cylinder SOHC fwd M.G. SaloonsThe 1300 M.G. Metro <strong>be</strong>longs here, but it fitted nicely on<strong>to</strong> the end of the ‘A’ series,so it is in that engine’s chapter. ‘O’, ‘R’, & ‘S’ series of engines all have cast iron cylinderblocks, with alloy cylinderhead <strong>an</strong>d gearbox-sumps. For the older enthusiast they arefull of modern metric threads with metric bolt & nuts heads. BL tried the R <strong>an</strong>d Sengine out, but it was not really a raging success, so the trusty ‘B’ series based ‘O’engine was resurrected, as you will see. Part of the ‘O’ series s<strong>to</strong>ry is under the MGBchapter, as it was the MGB’s 2 ltr engine stretch the series now used in these, cars grewfrom. It has <strong>be</strong>en in service since 1978 in the Morris Ital/Princess 1700, ( 1994cc in theau<strong>to</strong>matic Ital.) The Maestro is a shorter version of the Montego, by just two inches inthe wheelbase, <strong>an</strong>d without the 16" extra length of the boot, otherwise they arevirtually the same car.It is in this modern area that the DIY enthusiast <strong>be</strong>gins <strong>to</strong> losecontrol. On the XPAG <strong>an</strong>d ‘A’, ‘B’, <strong>an</strong>d ‘C’ series you could fix virtually everythingyourself. But c<strong>an</strong> you ‘re-chip’ a Montego? The engines of modern cars look afterthemselves, they ‘think’. These fwd engines have electric f<strong>an</strong>s that have sensors <strong>to</strong>measure water temperature, sensors <strong>to</strong> check ambient air temperature, <strong>an</strong>d even rpm,air density, <strong>an</strong>d throttle <strong>an</strong>gle for the Turbo powered versions. They need modern oils,no good putting 20/50 in these close <strong>to</strong>ler<strong>an</strong>ce units, they need good 10/40 quality oil,often a synthetic. If you are of <strong>an</strong> age where you went <strong>to</strong> the local h<strong>an</strong>dy garage, <strong>an</strong>dwound a h<strong>an</strong>dle on <strong>an</strong> oil pump <strong>to</strong> get a pint of commercial oil from a 45 gallon oildrum, <strong>an</strong>d serviced your own car, then a modern fwd M.G. would as<strong>to</strong>und you. The oilfilter is so easy <strong>to</strong> remove <strong>an</strong>d throw away, the engine oil is separate from the gearboxoil, not ‘Issigonis-in the sump’ as in the Mini <strong>an</strong>d Metro. Plugs screw in<strong>to</strong> <strong>an</strong> alloy head,<strong>an</strong>d need <strong>to</strong>rque setting <strong>to</strong> <strong>be</strong> correct on their tapered seats, <strong>an</strong>d <strong>to</strong> set a plug <strong>to</strong> .040",when you thought .025" a large gap. Electronic ignition is the reason for the powerfulspark, with no ignition points, but a tr<strong>an</strong>sducer (phonic sensor) on the flywheelhousing, that actually counts the rpm of the flywheel, using a tiny LED <strong>an</strong>d a pho<strong>to</strong>electriccell. When the correct gap at the correct degrees flashes by, pow, out goes thespark, modified <strong>to</strong> suit the rpm <strong>an</strong>d load. Like the V8, only correct cool<strong>an</strong>t must <strong>be</strong>used in this part-aluminium alloy/iron engine; forget <strong>an</strong>d it corrodes. Sparks plugswere 16mm, not 14mm, in the ‘O’ series.Maestro ‘R’ Series <strong>Engine</strong> (March 1983- April 1984)In March 1983 the LM10. ( now Leyl<strong>an</strong>d Mo<strong>to</strong>rs design office note,) was put on<strong>to</strong>the competitive car market in the UK, <strong>an</strong>d BL hoped it would save its flagging salesrecord. The car was a success, <strong>an</strong>d was powered by a dist<strong>an</strong>t relative of that ‘O’ seriesthat two MGB’s once had fitted back in 1980. The 1598cc ‘R’ series engine had <strong>be</strong>endeveloped from the ‘E’ series single ohc (sohc) 1700cc engine of the five speed Maxi, inits front wheel drive layout, (fwd.) The M.G. Metro was out on the streets, keeping theM.G. name alive, <strong>an</strong>d the LM10 was <strong>to</strong> provide <strong>an</strong> up market M.G. saloon. This smartup <strong>to</strong> date vehicle had a 16H 1598cc ‘R’ series engine, of four cylinders, with chaindriven single ohc, cast iron cylinder block <strong>an</strong>d aluminium alloy cylinder head, withtwin choke We<strong>be</strong>r 40DCNF carburetters, bore of 76.2mm <strong>an</strong>d a stroke of 87.6mm. MGhad modified the six ports of the st<strong>an</strong>dard car, having a head with enlarged ports <strong>an</strong>d a138

1.6 litre <strong>Engine</strong>‘R’ & ’S’ series139

20 HE Rover M16 in a MG Montego140

141Internal Components of the ‘O’ series

9.6 <strong>to</strong> 1 compression ratio. Camshaft timings were 20;52;55;17. It produced 103 bhp at6000rpm, with 100ft/lbs <strong>to</strong>rque at 4000 rpm. The st<strong>an</strong>dard Austin 1.6 Maestroproduced just 81 bhp. The MG car used a licence built Volkswagen Golf fwd five speedgearbox.M.G. Maestro 1600 ‘S’ Series <strong>Engine</strong> (April 1984- Oct 1984)In July 1984 the engine was improved <strong>an</strong>d redesigned in<strong>to</strong> the 1600cc ‘S’ series,16HE series, of 1598cc, with a <strong>to</strong>othed <strong>be</strong>lt drive sohc, new bal<strong>an</strong>ced cr<strong>an</strong>kshaft, <strong>be</strong>ttercylinderhead <strong>an</strong>d porting, thin-wall cast iron cylinder block lighter th<strong>an</strong> the ‘R’ series,with modified waterpump, oil pump, <strong>an</strong>d distribu<strong>to</strong>r drives. Carburetters <strong>an</strong>dequipment was as the ‘R’ series, with the head on the other way around. Inlet valveswere 1.5" dia, exhaust 1.218" dia. on both the R & S engines. Only 2,762 made <strong>be</strong>fore itwas discontinued. The ‘R’ <strong>an</strong>d ‘S’ series developed a bad name for problematical hotstarting in warm weather. The ‘S’ series was intended for the Montego as a <strong>be</strong>tterengine th<strong>an</strong> the ‘R’ series <strong>to</strong> which it was very closely related, but the Montego had the1994cc ‘O’ series. The ‘R’ <strong>an</strong>d ‘S’ must have <strong>an</strong> oil filter fitted that incorporates <strong>an</strong> <strong>an</strong>tidraindown valve, akin <strong>to</strong> unipart num<strong>be</strong>r GFE180. Some cheap versions do not havethis valve, <strong>an</strong>d the engine c<strong>an</strong> <strong>be</strong> started ‘dry’ of oil, leading <strong>to</strong> rapid wear.As mentioned in the MGB ‘B’ series chapter, the ‘O’ series was developed for use inthat sports car. It was <strong>to</strong> have <strong>be</strong>en a SOHC version of the engine, with twin SUcarburetters, or mech<strong>an</strong>ical fuel injection, with or without <strong>an</strong> exhaust powered turbocharger.As early as 1964 MG were looking at the ‘B’ series <strong>to</strong> make it a two litre. The1994cc block, gained by siamesing all the cylinders, went on <strong>to</strong> <strong>be</strong>come the ‘O’ series by1973 <strong>an</strong>d MG carried out its development for the USA market for the MGB. The ‘O’used the cr<strong>an</strong>kshaft <strong>an</strong>d a slightly redesigned block of the ‘B’ series, partially <strong>be</strong>causethe ‘new’ engine had <strong>to</strong> fit the existing fwd 1800 L<strong>an</strong>dcrab <strong>an</strong>d later Princess models.These had the 1798cc ‘B’ fitted. The Morris Marina was <strong>to</strong> gain the new engine as well,so a 1700cc version, as well as the 1994 version, was developed.The ‘O’ series had more ribbing th<strong>an</strong> the old unit, <strong>to</strong> stiffen the cast iron block, <strong>an</strong>d<strong>an</strong> aluminium head with cast camshaft cover. The cover also had the cam <strong>be</strong>aringsupper half, the actual valve clear<strong>an</strong>ces adjusted by shims. The SOHC was driven by a<strong>to</strong>othed <strong>be</strong>lt, <strong>an</strong>d the combustion cham<strong>be</strong>rs had sintered steel valve seats, thoughRover say these are not compatible with unleaded fuel. The ‘O’ weighed in less th<strong>an</strong>the ‘B’ series, with no rockers, push-rods, or cast iron head; 108lbs compared <strong>to</strong> 127lbs.The ‘O’s cr<strong>an</strong>kshaft was as the Marina 1.8, made of spheroidal graphite cast iron. Conrods were still forged with press-fit gudgeon pins. Pis<strong>to</strong>ns were die-cast with steelinserts <strong>to</strong> control exp<strong>an</strong>sion. The cylinderhead was a gravity die-casting, with a flatsurface, no combustion cham<strong>be</strong>rs. The cham<strong>be</strong>rs were in the pis<strong>to</strong>ns, now called a‘Heron-Head’, ( like the Jaguar V12.)Like the cr<strong>an</strong>kshaft, the camshaft was also of cast iron but r<strong>an</strong> in three <strong>be</strong>arings. Thelo<strong>be</strong>s bore directly on<strong>to</strong> the upturned bucket-type tappets. Oil pump, oil filter, <strong>an</strong>d oilpressure relief valve were all on <strong>an</strong> aluminium alloy die casting at the front of theengine. The pump fed in<strong>to</strong> a single oil gallery, not two as on the ‘B’ series. Both fuelpump <strong>an</strong>d distribu<strong>to</strong>r were driven off the SOHC, mounted on its cover. All nuts <strong>an</strong>dbolts are ISO metric threads. Ignition timing was by a disc on the cr<strong>an</strong>kshaft, with aslot at two points, <strong>be</strong>ing read by a light emitting diode watched by a pho<strong>to</strong>-electric cell.The DIY owner would not like the shims in the valve gear. Special equipment isrequired <strong>to</strong> set the gaps, as the cover is the upper <strong>be</strong>aring as well.142

As the MGB only saw two of these ‘O’ series, <strong>an</strong>d neither was sold, it was down <strong>to</strong>the Austin Princess <strong>to</strong> use it first, followed by the Marina. Initially the ‘O’ was lesspowerful th<strong>an</strong> the similar sizes ‘B’ series, but by the time it had <strong>be</strong>en fitted <strong>to</strong> the 1982Rover SDI 2000, with a twin SU HIF44 set up, there was 101bhp at 5,250rpm, <strong>an</strong>d 120lb/ft <strong>to</strong>rque at 3,250rpm, on a 9 <strong>to</strong> 1 compression ratio. An electric cooling f<strong>an</strong> <strong>an</strong>delectric fuel pump kept power losses down, <strong>an</strong>d the engine found its way in<strong>to</strong> the MGMontego by 1984, replacing the ‘R’ <strong>an</strong>d ‘S’ units. The engine gained Lucas fuel injectionas in the V<strong>an</strong>den Plas EFi, <strong>an</strong>d the MG used this as well. Rovers own single point EFi<strong>an</strong>d a twin OHC cylinderhead followed, but this 1987 118bhp engine went in<strong>to</strong> the 800Rover series as the M16, <strong>an</strong>d not a MG.The ‘O’ series was modified in<strong>to</strong> a diesel, used in the Sherpa v<strong>an</strong>, <strong>an</strong>d still built byPerkins of Peterborough, now called the Perkin’s Prima.M.G. Maestro 2.0 Efi litre ‘O’ Series <strong>Engine</strong> (Oct 1984-1991)M.G. 2.0i Montego <strong>Engine</strong> (1984-90)Oc<strong>to</strong><strong>be</strong>r 1984 saw a 1994cc M.G. Maestro, <strong>an</strong>d Montego ( LM11 ) with the 5 main<strong>be</strong>aring ‘O’ series engine in a fwd layout. ( See MGB for full ‘O’ series his<strong>to</strong>ry.)TheElectronic Ignition distribu<strong>to</strong>r was on the nearside, ( rear) end of the camshaft, on this‘O’ series, not half way along as on the Marina version. It was termed a 20H till 1989,then a 20HE99, <strong>an</strong>d had a cast iron block with alloy cylinder head. This <strong>be</strong>tter unit wasa 1994cc <strong>be</strong>lt drive sohc, with a bore of 84.5mm <strong>an</strong>d stroke of 89mm ( AGAIN!!) of 9.0 <strong>to</strong>1 comp. ratio, with Lucas Electronic ‘L’ type 11CU multi-point fuel injection, ( Bosch L-Jetronic built under licence,) <strong>an</strong>d fully mapped Lucas engine m<strong>an</strong>agement system, (called <strong>an</strong> ECU, engine control unit,) producing 117bhp at 5500 rpm <strong>an</strong>d 134lb/ft <strong>to</strong>rqueat 2800 rpm, ( 180Nm.). Inlet valves were 1.575" dia. of EN52 steel; exhaust 1.339" dia. of21-4-NS steel; <strong>an</strong>d camshaft timings were 19;41;61;15. This version had a licence built,five speed Honda PGM gearbox. In 1986 the camshaft cover had a cast in ‘MG’ motif<strong>an</strong>d details engine modifications. The Maestro was called the ‘EFi’, but ch<strong>an</strong>ged itsname <strong>to</strong> 2.0i in Oc<strong>to</strong><strong>be</strong>r 1987. Zero <strong>to</strong> 60mph was in 8.5 seconds. Like most modern cars,its fwd underbonnet was a mass of pipes <strong>an</strong>d ducts. Some of these models wereleadfree, but not until late 1989, ( after chassis 595500,) as Leyl<strong>an</strong>d Mo<strong>to</strong>rs were goingthe way of the ‘Le<strong>an</strong>-Burn’ engine, but governments were swayed by the ‘unleaded’lobby, catching quite a few m<strong>an</strong>ufacturers out, ( ie Ford for <strong>an</strong>other.) Unleaded MG carsused a Lucas MEQ 10072 for the unleaded petrol injection.M.G. Maestro 2.0 Turbo <strong>Engine</strong>. ( 1989-90) M.G. Montego Turbo <strong>Engine</strong>,(1985-90)In Oc<strong>to</strong><strong>be</strong>r 1988 500 examples of a turbo series of the 20H engine were fitted, with aGarrett T3 turbocharger <strong>an</strong>d intercooler, single electronic controlled HIF44Ecarburetter with variable choke, <strong>an</strong>d 8.5 <strong>to</strong> 1 compression. It was as the 20H, later20HE15, with sodium cooled exhaust valve stems, it produced 152bhp at 5100rmp <strong>an</strong>d169 lb/ft <strong>to</strong>rque at 3500 rpm, close <strong>to</strong> the ‘C’ series <strong>an</strong>d V8! Camshaft timings were13;47;55;21, <strong>an</strong>d gudgeon pins were fully floating, unlike the other versions with pressfit in the connecting rod. Pis<strong>to</strong>n rings were different on the Turbo, as were the valvecollet arr<strong>an</strong>gement. Zero <strong>to</strong> 60mph <strong>to</strong>ok just 6.7 seconds.Due <strong>to</strong> oil consumption on the Turbos, the valve stem oil seals were ch<strong>an</strong>ged fromVIN 554319, ( chassis num<strong>be</strong>r,) the new seal <strong>be</strong>ing combined with the seating. Inlet143

valves are flash-chromed for this seal, <strong>an</strong>d only later valves must <strong>be</strong> used, part No.UAM7713. Do not mix early <strong>an</strong>d late valves <strong>an</strong>d seals. During 1985 the 20HB engineson, had larger diameter cr<strong>an</strong>kshaft <strong>an</strong>d camshaft, a shorter cylinder block, ( termedthe ‘O2’, used on the later Rovers,) repositioned oil filter, oil pressure valve, <strong>an</strong>dalterna<strong>to</strong>r. It also had a modified water pump <strong>an</strong>d cam timing <strong>be</strong>lt <strong>to</strong>oth profile, <strong>an</strong>dslightly different <strong>be</strong>lt tensioner. Not the easiest turbo car <strong>to</strong> drive alas.Oil emulsification was a problem on all these models, the cold air hit a large sideexp<strong>an</strong>se, causing the vent system <strong>to</strong> clog up with ‘mayonnaise’. Austin/Rover dealersissued parts <strong>to</strong> affect a cure, though lagging the affected pipes helped. Other littlethings <strong>to</strong> give you grief were earthing the battery accidentally <strong>to</strong> the airflow meterbody, with a loose sp<strong>an</strong>ner perhaps. This simple action c<strong>an</strong> ruin the circuit board in the<strong>Engine</strong> Control Unit, (ECU ).The Rover 620 & 820 ( Sterling) ‘T’ series Turbo engine is often ‘borrowed’, for thelater MG Montego <strong>an</strong>d Maestro. This ‘super’ O2 series is called the ‘T’ series in theRover, <strong>be</strong>ing the last version of the ‘O’. There were 45,368 M.G. Montegos, <strong>an</strong>d 33,230M.G. Maestros made. Interestingly, if you add up the <strong>to</strong>tals of production give, youfind that 33% of all M.G’s ever made do not come from Abingdon, <strong>an</strong>d a similarpercentage are saloon cars...Hum!Use of the ‘O’ seriesMake & Modeldate introducedOriginal MGB installation, ( two only) Septem<strong>be</strong>r 1972-ish. development engines.1700cc Morris Marina/ Ital Septem<strong>be</strong>r 19782.0 Morris Ital Au<strong>to</strong>matic Septem<strong>be</strong>r 1978Austin Princess 2, 1700 ( wedge) July 1978Austin Princess 2, 2000 July 1978Austin Ambassador 1700 July 1982Austin Ambassador 2000 July 1982Sherpa v<strong>an</strong>1980, ( also as a diesel)Rover SD1 2000cc 1982M.G. Maestro 2.0 Oc<strong>to</strong><strong>be</strong>r 1990M.G. Montego 2.0i 1984M.G. Maestro EFi Oc<strong>to</strong><strong>be</strong>r 1984M.G. Maestro 2.0i Oc<strong>to</strong><strong>be</strong>r 1987M.G. Maestro Turbo Oc<strong>to</strong><strong>be</strong>r 1988M.G. Montego Turbo 1985Rover 820 1987, dohc cylinderhead as the M16,then improved <strong>to</strong> ‘T’ series.144

Chapter TenGEARBOXES <strong>an</strong>d AXLES (<strong>an</strong> overview only)It would <strong>be</strong> unfair not <strong>to</strong> at least mention these import<strong>an</strong>t components, as they putthe engines power on<strong>to</strong> the road. Under each model mention is made of the variousclutches used, <strong>an</strong>d on the pre-WW2 cars this fed the power in<strong>to</strong> a st<strong>an</strong>dard Morrisgearbox, with slightly modified ratios. Luckily the MG used the four speed versions, asm<strong>an</strong>y Morris cars only r<strong>an</strong> on three speed gearboxes until the Morris 10/4 series 2. TheTA for inst<strong>an</strong>ce used the Morris 10/4 series 3 gearbox with a lever extension, <strong>an</strong>dMorris ‘b<strong>an</strong>jo’, all welded tu<strong>be</strong> back axle, so called <strong>be</strong>cause with the differential (diff,)removed, it looked just like that instrument. These Morris rear axles are easy <strong>to</strong>identify, as the brakes are single leading shoe,(sls) with a large nut for each brake shoewear adjustment, <strong>an</strong>d have five studs per wheel. For the TA <strong>an</strong> adapter was fitted <strong>to</strong>use wire spoked wheels.The S,V,W, saloons simply used the gearbox <strong>an</strong>d rear axle fromthe similar sized Morris/Wolseley saloon, with bigger brakes <strong>an</strong>d wire wheel adapters.Also at the same time the TB gained the XPAG engine, it had <strong>an</strong> improved version ofthe the new Morris 10/4 Series ‘M’ four speed gearbox, with a selec<strong>to</strong>r extension fromthe <strong>to</strong>p cover. The same rear axle was used. On the heavy Morris saloon cars, this axlegained a bad reputation for breaking half-shafts. The YA gearbox is similar <strong>to</strong> the TB,but has a rear extension for the gear lever. The Wolseley 4/44 <strong>an</strong>d sv Morris Oxford/Cowley used the same gearbox, but adapted for column ch<strong>an</strong>ge.It was not until the arrival of the TD in 1952 that M.G. adopted the new Nuffieldrear axle, that split lengthways, <strong>an</strong>d used a tapered half-shaft end <strong>to</strong> located the hub on.This was fitted <strong>to</strong> the YB saloon, ( five studs,) the Wolseley 4/44, early 15/50, <strong>an</strong>d allthe Morris, Riley saloons, <strong>an</strong>d small commercial vehicles,( all with four studs,) some up<strong>to</strong> 1958, <strong>an</strong>d was designed for pressed steel wheels. Adapters were again needed forwire wheel conversions. At the same time this Nuffield rear axle was introduced,Austin were using their new all welded tu<strong>be</strong> ‘b<strong>an</strong>jo’ rear axle, introduced for theAustin A40 in 1947, <strong>an</strong>d the M.G. Magnette ZA has this fitted, along with the castaluminium Austin gearbox BMC adopted. This axle was for pressed steel wheels, ifwire wheels were <strong>to</strong> <strong>be</strong> fitted, half shafts <strong>an</strong>d adapters were needed. The gearbox of theZA onwards dates back <strong>to</strong> the Austin 12hp of 1935, with its three synchromesh gears on2nd, 3rd, <strong>an</strong>d <strong>to</strong>p. Second <strong>an</strong>d third synchromesh is very weak, <strong>an</strong>d often wears out in6000 <strong>to</strong> 7000 miles. This gearbox <strong>an</strong>d rear axle was fitted <strong>to</strong> all ‘B’ series M.G.s ( ie MGA,MGB, & Farina,) until the MGB adopted the stronger Sherpa v<strong>an</strong> four synchromeshgearbox in 1967. All except the Farina could have <strong>an</strong> overdrive fitted. The BMC b<strong>an</strong>jorear axle was used till 1967 on the MGB roadster, when it was replaced by a strongerSalisbury axle, again from the commercial half of BMC. The MGB GT had this axle fromnew, in 1965. Note the MGB wire wheel rear axle case is slightly narrower th<strong>an</strong> that forpressed steel wheels.The ‘A’ series M.G.s used the Austin A30 gearbox, itself dating <strong>to</strong> the Austin Eight of1935, <strong>an</strong>d adopted by BMC. It was fitted with a smaller b<strong>an</strong>jo rear axle again comingfrom the A30 of 1952. The A30 gearbox was put in<strong>to</strong> the sump of the Mini in 1959, <strong>an</strong>dso saw use in the ADO16 1100/1300 M.G.s. Luckily it was improved for the M.G. Metro1300. On the rwd Midgets, the filler <strong>an</strong>d level plug moved about, so it is possible <strong>to</strong>have <strong>an</strong> axle with a drain plug, <strong>an</strong>d no filler plug, or two filler plugs <strong>an</strong>d a drain plug,if you swap bits over. Early diffs had the filler on the nose casting, later on the rearb<strong>an</strong>jo cover. The Midget 1500 uses the Marina cast iron four synchromesh gearbox, its145

design coming from the same car the engine came from, the St<strong>an</strong>dard Eight of 1952, viathe Herald <strong>an</strong>d Spitfire. For those looking for second-h<strong>an</strong>d parts, the Marina 1100 V<strong>an</strong>used the BMC ‘A’ series gearbox <strong>an</strong>d b<strong>an</strong>jo rear axle, but the Marina 1300/1800 used allTriumph sourced parts.Au<strong>to</strong>matic cars such as that available on the Mk4 Magnette, Marina 1.8, the 1800MGB, <strong>an</strong>d the MGC, use the Borg-Warner type 35 gearbox, with a fluid-flywheel, (<strong>to</strong>rque converter,) instead of a clutch. The flexi-plate that bolts the <strong>to</strong>rque converter <strong>to</strong>the rear of the cr<strong>an</strong>kshaft has <strong>be</strong>en known <strong>to</strong> crack-up, spares are scarce.About mid 1962 BMC swapped over from eight ‘square’ splines on its gearbox firstmotion shafts <strong>an</strong>d axle half shafts, <strong>to</strong> twelve ‘star’ splines which are stronger <strong>an</strong>d wearless. Hence check half shaft ends carefully, <strong>an</strong>d fit the correct clutch centre plate. TheMGC <strong>an</strong>d MGB V8 used heavier gearboxes <strong>an</strong>d rear axles for obvious reasons, adaptedfrom the bigger BL/Rover saloon car/commercial r<strong>an</strong>ge. The major differences<strong>be</strong>tween the M.G. use of the Morris, <strong>an</strong>d later BMC axles, is the ratios AND the halfshaft lengths.During some production runs, M.G. ch<strong>an</strong>ged specifications, like the VA ch<strong>an</strong>gingfrom cork-in-oil clutch <strong>to</strong> a dry clutch, or the YA clutch <strong>be</strong>ing enlarged along with firstmotion shafts just <strong>be</strong>fore the YB, on the introduction of the TD. The Midget/Spritegained a diaphragm clutch when it went <strong>to</strong> the 1275cc engine, having earlier had thestronger rib<strong>be</strong>d gearbox fitting, itself following a clutch ch<strong>an</strong>ge. This causes problemswith clear<strong>an</strong>ce in the early cars <strong>be</strong>ll housing if a later clutch is fitted. The 1500 Midgethas a huge <strong>be</strong>ll housing on its Marina 1300 gearbox, as the same gearbox is used on theMarina 1800 <strong>an</strong>d 1800TC, with a big clutch. The Farina owner c<strong>an</strong> <strong>be</strong> caught out by theclutch centre splines, ch<strong>an</strong>ging <strong>to</strong> star splines on introduction of the MGB. Anyonewith problematical synchromesh on his MGA,ZA, Mk3 Magnette, c<strong>an</strong> do no <strong>be</strong>tterth<strong>an</strong> obtain the later Mk4 Magnette steel cones, that last a lot longer th<strong>an</strong> the brass onesoriginally fitted.The Longbridge M.G.s as they are termed, the fwd Maestro <strong>an</strong>d Montego, use eitherVolkswagen Golf, or Honda Accord/Triumph Acclaim based gearbox/drive units.The MGF uses that based on the Rover 200 series, on the end of the engine, not in thesump.No detail of modifications has <strong>be</strong>en entered in<strong>to</strong>, <strong>an</strong>d there were lots of them. Seeyour workshop m<strong>an</strong>ual, or write a book on them.146

Limited ProductionsThe MG C six cylinder, once shunned, now a cult car.The MGB reborn? A MG RV 8 under bonnet view.147

Chapter ElevenConclusionWhere To From Here?Inside the MG s<strong>to</strong>ry are engines that never made it <strong>to</strong> the public. Others eventuallywere used, but not m<strong>an</strong>y knew from whence the engine came. The V4 engines were justBMC copying other people like Ford, ( whose UK V4 was a terrible engine, <strong>an</strong>d eventhe Germ<strong>an</strong> Ford V4 used a counter-shaft <strong>be</strong>cause of bal<strong>an</strong>ce problems.) The ‘O’ serieswas made for the MGB, <strong>to</strong> give the car further life. This single ohc c engine would haveimproved the car, especially with the fuel injection <strong>an</strong>d turbo offered as well. Abingdonwas closed the year this engine was ready for the USA pollution-free market. The ‘O’went <strong>to</strong> the Morris Marina, then the Montego <strong>an</strong>d Maestro. The ‘O’ has the DNA of the‘B’ series, <strong>an</strong>d the Rover M16 engine is a twin ohc version.Was the M.G. 1275cc Midget engine deli<strong>be</strong>rately kept 5 bhp less th<strong>an</strong> the 1275ccM.G. 1300’s 70 bhp so as not <strong>to</strong> seriously embarrass the MGB? Or did BMC simply notinvest <strong>an</strong>y more <strong>to</strong> improve the cars? The last MGBs, Midget, <strong>an</strong>d MG1300 were allwithin about 2 seconds of each others 0 <strong>to</strong> 60mph times during the late 60’s <strong>an</strong>d early70’s.<strong>Engine</strong>s used in M.G. cars are varied <strong>an</strong>d often unexpected by the uninitiated. A TAMidget with a Series 3 Morris Ten/4 engine indeed. A M.G. Midget with a MorrisMinor engine, or a Triumph Spitfire engine <strong>an</strong>d Marina gearbox indeed. Or a MGBwith <strong>an</strong> Austin Westminster engine, ( MGC). Or <strong>an</strong>other MGB with a L<strong>an</strong>drover V8engine. Or a MG Maestro with a Mk2 Marina engine. This is not the real case as weknow, often M.G. were used <strong>to</strong> test a new engine <strong>an</strong>d develop it for future reliable usein millions of other cars, then going on <strong>to</strong> improve it for MG use <strong>an</strong>d racing success.The 1275cc MG Midget ‘A’ series <strong>an</strong>d Midget 1500, the 1498cc, 1588cc <strong>an</strong>d 1622ccMGA ‘B’ series, as well as the 1798cc MGB ‘B’ series are all available as fullyreconditioned ‘exch<strong>an</strong>ge’ unit from the big M.G. Suppliers. These c<strong>an</strong> <strong>be</strong> had leaded orlead free, or even bored out <strong>to</strong> 1340cc for the Midget, <strong>an</strong>d 1980cc for the MGB, invarious stages of tune. They are not cheap, but show how popular these BMC/BLengines still are, as those for the Morris Minor, Austin A40 Farina, <strong>an</strong>d A35 c<strong>an</strong> still <strong>be</strong>found from the specialists, as c<strong>an</strong> those for the Farina family saloons. All good news,not simply <strong>be</strong>cause the engines were used by so m<strong>an</strong>y for so long, but <strong>be</strong>cause theywere well made. The more specialised engines MG used, like the ‘C’ series <strong>an</strong>d RoverV8, are available on order, <strong>an</strong>d a warning, they are not cheap at all. But all of theengines in this book c<strong>an</strong> <strong>be</strong> DIY res<strong>to</strong>red, as most machine shops will <strong>be</strong> able <strong>to</strong> sourcethe necessary new pis<strong>to</strong>ns, shell <strong>be</strong>arings, etc. All other parts are easily found at thespecialist suppliers. Only the three main <strong>be</strong>aring 1798cc MGB engine suffers fromdifficulty of supply, <strong>an</strong>d that is in its slightly larger steel backed shell <strong>be</strong>arings, lowdem<strong>an</strong>d not producing a supply. If we do not use them, bits will not wear out, then noone will make new bits. Then when we do need something...Long engine life relies on regular servicing <strong>an</strong>d usage, <strong>an</strong>d things like oil <strong>an</strong>d oilfilter ch<strong>an</strong>ges must <strong>be</strong> carried out. Austin FX series London Taxis are started up onemorning, <strong>an</strong>d c<strong>an</strong> <strong>be</strong> run for ages, only <strong>be</strong>ing s<strong>to</strong>pped <strong>to</strong> fill the fuel t<strong>an</strong>k <strong>an</strong>d check oillevels, then off again, for months at a time. They last for 250,000 miles or moresometimes, without repair, always <strong>be</strong>ing hot. If the car is little used, halve the servicing148

periods <strong>to</strong> s<strong>to</strong>p corrosion, as short cold runs build up acids <strong>an</strong>d water in the oil, whichwill eat away import<strong>an</strong>t metal surfaces. It is <strong>be</strong>st <strong>to</strong> get everything really hot, cover theradia<strong>to</strong>r <strong>to</strong> impede air flow <strong>to</strong> speed up the warming up, use the choke as little aspossible, <strong>an</strong>d run it for at least 30 minutes if you are doing a ‘winter start up’ in thegarage. To reduce noise pollution for my neighbours, I put <strong>an</strong> old mo<strong>to</strong>rcycle silencerover the exhaust pipe, it cuts down the noise considerably in a small place. Have plentyof ventilation, Carbon Monoxide from the exhaust is odourless <strong>an</strong>d tasteless, youc<strong>an</strong>not see it, <strong>an</strong>d it kills.We are <strong>to</strong>ld that by the year 2000 leadfree fuel will <strong>be</strong> all that is available. Bewarethe confidence trickster who will try <strong>to</strong> sell you ‘tin balls’ <strong>to</strong> put in<strong>to</strong> your fuel t<strong>an</strong>k, or<strong>an</strong>y other ‘inst<strong>an</strong>t’ additive that purports <strong>to</strong> cure valve recession. They are all rubbish,<strong>an</strong>d if they did work ALL m<strong>an</strong>ufacturers would have fitted them years ago. Either, as Ihave done, fit hardend steel inserts <strong>to</strong> your cylinder head, or hope the large petrolcomp<strong>an</strong>ies come up with a cheap additive that WORKS. If you need a leadfree head, allspecialists do exch<strong>an</strong>ge leadfree, at reasonable prices. If you are poor, have just theinserts fitted by a machine shop, <strong>an</strong>d re-cut. Then buy a set of exhaust valves <strong>an</strong>dphosphor-bronze valve guides, assemble your head yourself, at about half the abovecost, ( ie use Metro leadfree exhaust valves in your Midget head, from your RoverGarage; or USA spec MGB ones from most MG Specialists.) Long fast runs on leadfreepetrol, in <strong>an</strong> unmodified engine, will ruin exhaust valve seats, you might just get awaywith creeping about at 30mph for a few years, but eventually the seats will just burnway. Grey cast iron was never me<strong>an</strong>t <strong>to</strong> <strong>be</strong> used without tetra-ethyl-lead in the petrol. Itwas first added <strong>to</strong> boost the ‘oct<strong>an</strong>e’ rating in the 1930’s, but was quickly found <strong>to</strong> alsoprotect exhaust valve seats, <strong>an</strong>d lubricate valve stems, allowing the use of cheapermaterials. Any car that c<strong>an</strong> run on leadfree fuel, c<strong>an</strong> use a two-way catalyst. Good newsif the EEC insist all cars are <strong>to</strong> <strong>be</strong> so fitted, only the high price of the little stainless steel,precious metal lined, ceramic centred, tiny silencer box item is the problem. Over use ofthe choke, or a worn engine burning oil, will ruin a catalyst in seconds. Interestingly,pis<strong>to</strong>n engined aircraft still use high oct<strong>an</strong>e, 100/130 gasoline, with tetra-ethyl-lead(tel) added.The cost of rebuilding the common engines, like the XPAG, ‘A’ <strong>an</strong>d ‘B’ series isrising. Old-s<strong>to</strong>ck items are <strong>be</strong>ing used up, <strong>an</strong>d MG Specialists are having <strong>to</strong> rem<strong>an</strong>ufactureparts, so costs will have <strong>to</strong> rise <strong>to</strong> cover the investment required. If you arelucky, keep your eyes open at garage sales <strong>an</strong>d au<strong>to</strong>jumbles. Look at the enginenum<strong>be</strong>rs on everything. For inst<strong>an</strong>ce if you see 48G 430 on <strong>an</strong> engine, you have founda Gold Seal rebuilt Mk4 Magnette 1622cc engine, that will fit a 1600 mk2 MGA. Or 8G205R that shows a Gold Seal MG ZA 1489cc engine, good for a 1500 MGA as well. ( 8Gwas first used for ALL reconditioned engines, till about 1956, when 8G me<strong>an</strong>t ‘A’ series,48G me<strong>an</strong>t ‘B’ series, <strong>an</strong>d 68G me<strong>an</strong>t ‘C’ series.)Every book has a deli<strong>be</strong>rate mistake, in this one it is the rounding up of the ‘B’ Seriesstroke at 89mm. It was actually 88.9mm. Did you notice?149

Index <strong>to</strong> ChaptersOne; MG <strong>Engine</strong>s Care of Morris 8Morris & MG early his<strong>to</strong>ry 8Production of <strong>an</strong> engine 10Two; TA Midget Onwards 12No more racing!....Use of Morris saloon engines 12<strong>Engine</strong>s of the VA, SA 14<strong>Engine</strong>s of the WA, TA 17Three; X Series of <strong>Engine</strong>s 25His<strong>to</strong>ry of the XPAG 25<strong>Engine</strong> identity & num<strong>be</strong>ring 31XPAG modifications during production 32Identity found on engines 39Camshafts 39<strong>Engine</strong>s of the TB, TC, TD, TF, YA, YB, YT, & Wolseley 4/44 43Four; State of the Art of XPAG 46What does my MG have fitted? 46Reconditioned engines 47Block identity 50Five; BMC ‘A’ Series & Triumph 56BMC ‘A’ series his<strong>to</strong>ry 56<strong>Engine</strong> num<strong>be</strong>ring, ( including ‘A’, ‘B’ & ‘C’ series) 58Large use of the ‘A’, model by model, 1952 <strong>to</strong> 1990 58Identifying the engine 58Cylinder heads 74Camshafts 77His<strong>to</strong>ry of the Triumph 1500 engine, 78<strong>Engine</strong>s of the Midget Mk1, 1 1/2, 2, 3, Mk3 1500,MG 1100, MG 1300,73 onwardsMG Metro 1300, MG Metro Turbo, MG Metro 6R476 onwardsSix; BMC ‘B’ Series in MG 84His<strong>to</strong>ry of the ‘B’ 84Large use of the ‘B’, model by model, 1953 <strong>to</strong> 1980 88Modifications during production 90Camshafts 91Cylinder heads, 91<strong>Engine</strong>s of ZA, ZB, MGA 1500, EX182, MGA1600, MGA1600 Mk2,MGA Twin Cam, Mk3 & Mk4 Magnettes99 onwardsBlue Streak six cylinder development 106Seven; A Big ‘B’ Series 112<strong>Engine</strong> of MGB & MGB GT 1962 <strong>to</strong> 1980 113V4 & ‘O’ series in MGB, & Marina 1800 116, 118OHC ‘O’ Series s<strong>to</strong>ry 116150

MGB engine series 117MGB cylinderheads 121Eight, Those Other MGB’s, & the MGF 121‘C’ Series engine his<strong>to</strong>ry 121Use of the ‘C’ series, model by model 122<strong>Engine</strong> of the MGC 124Rovers Buick V8 his<strong>to</strong>ry 125Use of the V8 model by model, 1960 <strong>to</strong> date 131<strong>Engine</strong>s of MGB GT V8, MG RV8 127, 128‘Rover ‘K’ series his<strong>to</strong>ry 131<strong>Engine</strong> of the MGF 131Nine; Rover, ‘O’, ‘R’, <strong>an</strong>d ‘S’ Series 138, 142Austin/Rover short his<strong>to</strong>ry 142<strong>Engine</strong>s of the MG Maestro 1600, Maestro 1600S,Montego/Maestro 2.0i, & Turbos,142 onwardsTen; Gearboxes <strong>an</strong>d Axles (<strong>an</strong> overview only) 145All with <strong>an</strong>ecdotes of past experiences.151

Picture SourcesPartly sectioned 1 1/4 litre MG engine. Staff artist of ‘Light Car’ magazine May ’48Twin SU carbs on the MG SA Two Litre. The Au<strong>to</strong>car, Oct 4th 1935SU carbs 1939 TB Midget The Au<strong>to</strong>car Sept 8th 1939Twin SU’s of TA & 1 1/2 ltr VA, Encyclopaedia of Mo<strong>to</strong>ring, Sporting Cars, 1936TA water pump, <strong>an</strong>d Acceleration car<strong>to</strong>on, ,, ,,MPJG MG Midget TA engine,exploded view, Light Car, March 10th 1939MPJG TA cylinderhead cross section, Light Car March 17th 1939.Morris 10 series ‘M’ 1140cc engine, drawing. Morris Ten series ‘M’ service data19391250cc XPAG ‘Y’ series engine, drawing, ‘Y’ series workshop m<strong>an</strong>ual, (MGOC)1250cc XPAG ‘Y’ engine, cross section, ,, ,, ,,MG TF Midget engine cross section, ‘TF’ ,, ,, ,,Wolseley 4/44 engine end view, Workshop M<strong>an</strong>ual Wolseley 4/44 & 15/50XPAG/XPAW/XPEG oil system, ,, ,, ,,MG TD engine in situ,Au<strong>to</strong>car.Morris Minor series 2 engine lubrication. Workshop M<strong>an</strong>ual for Morris Minor .Cross section of early ‘A’ series ,, ,, ,,MG Midget Mk1 engine, open view,MG Midget Workshop m<strong>an</strong>ual,Haynes.St<strong>an</strong>dard Eight engine end view, drawing, St<strong>an</strong>dard Eight car h<strong>an</strong>dbook.MG 1100 power unit.Workshop M<strong>an</strong>ual 1100/1300, Haynes1275cc cr<strong>an</strong>kshaft exploded view,Morris Marina BL Opera<strong>to</strong>r & RepairM<strong>an</strong>ual.Original Austin A40 engine,Book of the A40 Devon, Cassell, London.BMC ‘B’ series engine open view, Au<strong>to</strong>car, April 12th 1957First 1489cc ‘B’ series, forward sump, Mo<strong>to</strong>r Trader 30th Oc<strong>to</strong><strong>be</strong>r 1957End view, 1489cc ‘B’ series,Wolseley 15/50 Workshop M<strong>an</strong>ual BMCSide view, 1489cc ‘B’ series engine, ,, ,, ,,MGA Twin Cam engine, M.G. Cars from 1934, Pearson 1958.MGA engine in situ, Au<strong>to</strong>car, 1955MGB engine in situ, Au<strong>to</strong>car, 1962Five main <strong>be</strong>aring in sump of 1800 ‘B’ series Morris Marina Opera<strong>to</strong>r & Repair M<strong>an</strong>ual,BL’C’ series in Riley 2.6, The Mo<strong>to</strong>r, August 28th 1957‘C’ series engine, end view,Wolseley 6/99 Workshop M<strong>an</strong>ual, BMCRover V8 in P6B, Au<strong>to</strong>car April 18th 1968‘E’ series engine, open view,Austin Maxi Workshop M<strong>an</strong>ual, BL.Rover K16 engine cylinderhead,Rover K16 oil system}Haynes M<strong>an</strong>uals.Montego/Maestro Fuel injection, „R & S series engine exploded view, „‘O’ Series camshaft, „‘O’ Series internal components. „152

MG saloonsFour MG saloons, the poor relations in the MG world. Above a ZB Vari<strong>to</strong>ne, <strong>an</strong> au<strong>to</strong>matic MK4 Magnette,<strong>be</strong>low a YB, <strong>an</strong>d <strong>to</strong> the left a fwd 1100.** All Pho<strong>to</strong>s Copy right <strong>to</strong> the author. **153