Brian Rupnow build--Hit and Miss air/steam engine « on: June 11 ...

<strong>Brian</strong> <strong>Rupnow</strong> <strong>build</strong>--<strong>Hit</strong> <strong>and</strong> <strong>Miss</strong> <strong>air</strong>/<strong>steam</strong> <strong>engine</strong>
<strong>«</strong> on: June 11, 2009, 06:04:03 PM » Quote
This might end up being a long thread. I started it over on the "Break Room" under the heading
"<strong>Hit</strong> <strong>and</strong> <strong>Miss</strong> Steam Engine???"
http://www.homemodel<strong>engine</strong>machinist.com/index.php?topic=5150.0
Then drew up mechanical details <strong>and</strong> posted them in the download section.
http://www.homemodel<strong>engine</strong>machinist.com/index.php?action=tpmod;dl
And today I started whittling out parts.
Beginning of cylinder <strong>and</strong> crankcase---

Thanks Maryak---Here we have the crankcase roughed out on the b<strong>and</strong> saw, (the radiuses was
put in with a 3/8" drill thru) ---<strong>and</strong> a bit of blatant advertising.

So today I undertook the first step in actually machining the crankcase. I used a 5/8" diameter, 4
flute, end mill <strong>and</strong> milled to the lines that were scribed when I laid the crankcase out. I snuck up
on the lines then measured with my vernier caliper when I got real close to the line, so as not to
cut beyond the line.

Son of a gun! This thing is small. (but bigger bore <strong>and</strong> stroke than Elmer’s <strong>engine</strong>s.) That’s the
one thing about designing in 3D—It is hard to get a "feel" for how big or small something is
from just the 3D cad model. I know that in my "full size" machines that I design, I have a "full
size" model of a man which I insert into the assembly model so my customers can get a sense of
"how big" the finished machine will be.

Here we are putting the slot in the center of the crankcase. I got this far <strong>and</strong> realized that A--I
don't have a 5/16" end mill to get the 0.156 radius called for on my drawing, <strong>and</strong> that B--I had a
3/8" end mill but it was too short. So, as usual, I cheated. I used my 3/8" end mill (which ends
up giving me a .188 radius instead <strong>and</strong> I slid a 0.34" long spacer into the collet before I put the
end mill into it, to make the end mill long enough from the collet shoulder to the end of the end
mill. This is probably a horribly dangerous <strong>and</strong> inadvisable thing to do. but it solved the problem,
<strong>and</strong> it worked well.

Boring hole in crankcase for the cylinder---
Cylinder attached to crankcase:

This evening I've been making the piston. I have no idea whether I'm going about this correctly
or not, but it’s working, so it must be okay. I have a piece of 1" brass plate about 4" square, so
first I cut a 1" wide strip off the side, center drilled the ends, set it up between centers <strong>and</strong> turned
it to 0.75" dia. (You can't see it but there is a center gripped in the 3 jaw chuck.)
This is something I forgot to show in my detail drawing.--A couple of grooves to hold
lubricating oil, about 0.015 deep by 45 degrees on the cylinder. (in this picture I have parted the
square end off <strong>and</strong> clamped the round part in the 3 jaw chuck.)

Now here is the part I like--Since I still had the square shank left on one end, after parting off,
which gave me something to hold in my milling vice, I set it up in the vice <strong>and</strong> milled the slot
<strong>and</strong> it was nice <strong>and</strong> secure.
So here we are, as far as I'm going tonight. All that remains to be done is put in the 0.125 wrist
pin hole <strong>and</strong> part it off to length.

Now we have a finished piston. This is a complete reversal of the st<strong>and</strong>ard "Brass cylinder <strong>and</strong>
aluminum piston". What was my reason for doing it this way?---Only that I had brass <strong>and</strong>
aluminum in stock to <strong>build</strong> it this way, <strong>and</strong> didn't want to spend money to buy more material.
From an <strong>engine</strong>ering viewpoint, probably its better the other way, because an aluminum piston
weighs much less, therefore would have much lower reciprocating inertial force, but for these
little demonstration <strong>engine</strong>s, I doubt it makes any difference.
I just found a mistake on the crankcase drawing. (Yeah, I do make mistakes!) The hole centers
for the bearing blocks should be 0.588 not 0.538 as previously posted. This drawing is updated.

I turned the Bearing Supports. (No Photo) It was while drilling <strong>and</strong> tapping the crankcase for
these that I discovered the mistake in the previous post. At least I got lucky <strong>and</strong> discovered the
error in the hole spacing on the crankcase BEFORE I drilled <strong>and</strong> tapped it!!! Glad I didn't drill
<strong>and</strong> tap the crankcase first <strong>and</strong> THEN go to make the bearing blocks.
Excuse my question...very little experience...but what is turning the part? Is there a pin or
something on the end of the part that the chuck jaw is against?
Zee--I wondered if anybody would pick up on that!!! Yes, when I center drilled the end which
sits closest to the chuck, I put a 0.125 hole in one corner <strong>and</strong> stuck a piece of 1/8" x 1.5" steel rod
in it. One of the chuck jaws riding against the side of the pin turned the part. That is my secret
trick for avoiding having to change to <strong>and</strong> use my 4 jaw chuck.)
Did you de-burr the edges of the crankcase? They look awfully sharp to me.
No, I haven't de-burred anything yet. All my tooling is well used (read that as dull to really dull),
<strong>and</strong> it pulls a horrible burr on aluminum. When I get a piece off the mill, I set it up in my
workbench vice <strong>and</strong> flat-file all the offending burrs so that they won't give a false reading in a
further set-up, but the sharp corners will remain until I get to the "cosmetic" stage of the project.
They are not really as sharp as they appear in the picture--not to the point where they would cut
my h<strong>and</strong>. I will eventually use some medium emery cloth to "break" all the sharp edges, prior to
polishing. I am going to try something new <strong>and</strong> rather terrifying---machining a crankshaft from
solid. I have these two instruction sheets prepared by Chuck Fellows, <strong>and</strong> since this is a
relatively simple crankshaft, I will try it <strong>and</strong> see what happens.

So---This afternoon was a br<strong>and</strong> new learning experience for me. After reading as much as I
could from those who have boldly gone before me, I set out to machine a one piece crankshaft. I
followed Chuck's guide drawings, <strong>and</strong> laid the crankshaft out on a piece of 3/8" x 1" cold rolled
steel bar stock, then drilled <strong>and</strong> sawed out the center. The 3 x's are there so that I take all of my
measurements from the same side of the bar during layout.
I then made the long saw cuts, <strong>and</strong> then lay out <strong>and</strong> center drilled the ends of the bar, using my
mill.

Then it was over to the lathe to mount the bar between centers to turn the connecting rod journal.
If you look at the end closest to the chuck, you can see that I have a piece of 5/8" round stock
with a 30 degree taper turned on the end of it to become my "center" in the chuck. I was able to
slide the end of the bar between 2 of the jaws, <strong>and</strong> that was what actually made the part turn. I
found it VERY SCARY to cut that journal with the cut off tool stuck out about a mile as shown
in the picture.---<strong>and</strong> Oh, Yeah---I made the crankshaft 1" longer than I needed so that I could cut
off the ends with the center drill holes in them <strong>and</strong> still end up with the finished crankshaft the
correct length.
And this is what it looked like before I set up to turn the ends. The 1/4" bolt has a nut <strong>and</strong> washer
on the far side, <strong>and</strong> is tightened down to keep the slot in the center from collapsing when I turn
between centers.

Here we are turning the first end to finished diameter. See---I do own a lathe dog!!! Once the
first end was finished I turned the part 180 degrees <strong>and</strong> finished the other end the same way.
The finished one piece crankshaft---

And here is the crankshaft in its new home.
This afternoon I built the connecting rod <strong>and</strong> cap. --Here is a good tip---If you start with a piece
of 1" x 1/4" brass bar, you can use a 3/8" end mill to plunge cut at the center of the 4 radii <strong>and</strong>
then go ahead <strong>and</strong> cut slots which will form the corner radii at each end <strong>and</strong> remove most of the
unwanted material.--there will be enough brass left between the cutter <strong>and</strong> the vice jaws that the
cutter doesn't hit them. I modified the con rod drawing a little bit, so will post a new drawing
here <strong>and</strong> update the download section later.

This is the way the connecting rod turned out. The cap has to be bolted to the rod before the bore
is put in, because half the bore is in the cap <strong>and</strong> half in the rod.

And here we have the con rod, cap, <strong>and</strong> piston. For those who might have been wondering, I'm
going to use a piece of 1/8" cold rolled steel round rod for a wrist pin, <strong>and</strong> I will use a bit of #648
Loctite to keep the pin positioned in the piston.
Nothing too exciting this morning, but still I spent 4 hours hogging this steel flywheel out of a
piece of 3.25" diameter round mild steel.---Yes, I know that the plans call for 3 1/2" diameter,
but this is what I could get CHEAP. I decided that aluminum flywheels just don't weigh enough
to give the inertia needed for a good "hit <strong>and</strong> miss" action. I will probably make both flywheels
out of steel---The second one won't be as much work, as it doesn't have an extended hub like the
one I just finished. I think maybe I will paint these flywheels to keep them from rusting. Brass
would have been nice, but it’s just too spendy.

Talk about famous last words---"The second flywheel shouldn't be as much work as the first."
So there I was, merrily machining the recess in the face of the second flywheel, <strong>and</strong> making
calculations as to how much more I have to take of the hub to get it to 0.75" diameter.--I dunno
what happened--STUPID ATTACK MAYBE!!! Damn, that hub is starting to look kinda small.
Hmmmm--maybe I should measure that. HOLY SNOT!!! 0.61 DIAMETER!!! So---There is
too much work invested to scrap it <strong>and</strong> start over---Out to the garage <strong>and</strong> get out the mig welder-
--<strong>build</strong> the hub back up---

If I had made that second flywheel out of brass or aluminum, I'd have had to throw it in the trash
can. As it turned out, mild steel is one of the most easily welded metals that exists, <strong>and</strong> 5 minutes
with the mig saved my day!!! I still have some minor holes to add <strong>and</strong> some serious polishing to
do on the flywheels, but by <strong>and</strong> large they are finished. I have worked 8 hours to make 2
flywheels.

Better find a new supplier. ENCO has taps for US$2.95...
http://www.use-enco.com/CGI/INSRIT?PMAKA=325-
4769&PMPXNO=5809855&PARTPG=INLMK32
Okay---Its update time. First of all, thanks for that link Marv---I am going to find a source of
cheaper taps.--I was tapping the holes in the end of the cylinder which attaches to the crankcase
when I broke the tap off in the third hole. My "fix" will be to rotate the cylinder 10 degrees <strong>and</strong>
D&T 4 new holes ---nothing lost!! I got my #5-40 SHCS from the nut <strong>and</strong> bolt store, so was able
to bolt the connecting rod cap into place, then drill <strong>and</strong> ream it to fit on the crankshaft. After
MUCH filing <strong>and</strong> fiddling, everything rotates quite nicely, with the piston moving back <strong>and</strong> forth
in the bore of the cylinder smoothly. I decided that I didn't want holes through the outer rim of
the flywheel like my plans call for, so I just drilled <strong>and</strong> tapped a #10-24 hole in the extended hub
of the "non-governor" flywheel. I have one of those kinky vices that will rotate into many
strange configurations, so I put the set screw hole into the flywheel governor at an angle as
shown in the picture. I still haven't undertaken any "cosmetic" work on any of the parts, so they
look a bit rough.--My plan is to make all the parts, test assemble them, then to blow it all apart
for polishing.

Spent today attending to a myriad of things--- I stopped at my metal suppliers <strong>and</strong> picked up
enough brass to <strong>build</strong> the cylinder head <strong>and</strong> all the other tiny bits. I re-drilled <strong>and</strong> tapped the

cylinder, (both ends) successfully this time, <strong>and</strong> while I had things apart I spent an hour on the
polishing wheel. The flywheels have all the appropriate cutouts <strong>and</strong> slots now.
This morning I built the cylinder head. the very first thing I noticed was that I had left a
dimension off the drawing which locates the 0.375" reamed hole.---Since I wanted to use my

3/8" end mill to do a plunge cut to form the 0.188 radius between the two circular ends, I added
in the dimensions of where that circle would be. (see red circle--that is the center of the radius).
I cut it from a 3/8" x 1.5" piece of brass bar. Everything worked out very well.

Not too much to say about the exhaust gl<strong>and</strong>, other than that is finished <strong>and</strong> it fits. I turned it
from 1" round brass. then used a piece of 1/4" round cold rolled about an inch long as an
alignment guide when I assembled it to the cylinder head to keep the 1/4" reamed holes lined up.
I bolted it in place, still with the 0.1" thick part a full 1" in diameter. Then I scribed around it,
removed it from the cylinder <strong>and</strong> milled away the excess, leaving it rectangular to match the
cylinder.
This morning I built the lower <strong>and</strong> upper halves of the valve body. I didn't have any tooling that
was small enough to reach into the lower valve body <strong>and</strong> turn the 45 degree angle. I didn't want
to go out <strong>and</strong> buy another piece of tooling for a one time use, so I started looking through my
shelves to see what else I could possibly use, <strong>and</strong> discovered a bunch of countersinks that I had
very seldom used. They have an included angle of 82 degrees, not the 90 degrees called for on
the drawings, but--Hey---I can turn the valve itself to match whatever the valve seat is. I turned a
bit off the outer diameter of the countersink so that it would fit into the 0.438 bore with a bit of
clearance, <strong>and</strong> used it to turn the angled seat in the lower valve body.

This afternoon I built the rest of the valve. I hate working on stuff this small, but the valve does
work. I discovered that with the bolt circle originally called up I simply ran out of room. I had to
increase the bolt circle, so there will be 2 more drawings that change to reflect this larger bolt
circle in the upper <strong>and</strong> lower half of the valve. In this first picture, you can see how I cranked the
compound rest around to allow me to turn an 82 degrees angle on the end of a piece of brass. I
then reamed it to 0.093 <strong>and</strong> inserted the valve stem. Since the steel valve stem was inserted into a
blind hole, <strong>steam</strong> <strong>build</strong> up during silver soldering tries to pop the stem out of the brass. To
overcome this I clamped the brass in my mill vice <strong>and</strong> brought the chuck down to rest on top of
the steel valve stem so it couldn't pop out, then I soldered it right in the vice. After the soldering
was finished, I put it back into the lathe to clean it up <strong>and</strong> get silver solder off the valve face.

This is the finished valve assembly. Of course, I have to shorten the bolts so that they only come
flush with the underside of the lower valve body.--And somehow I have to figure out how to put
a 0.024 wide slot into the bottom of the valve stem for an e-clip. (maybe use the sharp corner of a
cut off tool???) NOW I NEED SOME HELP---Even though I took great care when making the
valve <strong>and</strong> the lower valve housing, it still leaks a bit of <strong>air</strong> with the valve closed. I seen mention
of using some silicone on the valve seat (I think) in one of the other posts of people who built
this <strong>engine</strong>, but I didn't see any detailed description of how to do that---can someone please jump
in <strong>and</strong> tell me a bit more about that.

And here are the updated drawings, as promised, with revised bolt circles.

I decided to make the "SOLDERED ASSEMBLY OF BACKING PLATE" from a single piece
of brass. I milled out the shape, <strong>and</strong> then had to figure out how to put the 1/16" slot in it. I had
never used a slitting saw before, so this gave me a chance to buy some new tooling. (Which is
always good!!!) I bought a 1/6" x 2" diameter slitting saw <strong>and</strong> arbor, <strong>and</strong> after some head
scratching, decided to set it up as shown. The operation worked perfectly, <strong>and</strong> I also drilled the
two 1/16" diameter holes in the same set-up.

I just finished the "CAM ACTUATOR BUSHING" <strong>and</strong> the "SLIDING CAM" . They look a bit
grubby in this picture because I had coated them with oil <strong>and</strong> worked them back <strong>and</strong> forth on a
piece of 1/4" rod to get them meshing smoothly. (Note to self--Clean parts BEFORE taking
pictures!!!)----now I have to call my friend <strong>and</strong> see if he has a #0-80 tap <strong>and</strong> drill.

About your valve problem. Consider making an interference angle on the valve, by which I mean
the angle on the valve is 1 to 11/2 degrees less than the valve seat angle. The interference idea
being to get a valve seal as narrow as possible. A very narrow seat is common practice on most
internal combustion <strong>engine</strong>s. You could also consider lapping the valve to the seat, now that you
have a slitting saw cut a little bit if a grove in the top of the valve head, not right across but just
wide enough for a screw driver. Use a fine lapping compound <strong>and</strong> a back <strong>and</strong> forth twisting
motion with a screw driver to clean up <strong>and</strong> polish the seat. You are making excellent progress,
enjoy seeing your work.
Thanks Ernie--I considered lapping the valve, ---its easy enough to do because the shank sticks
out through the bottom of the valve housing. In the end I took the easy way out---since I run my
<strong>engine</strong>s on <strong>air</strong>, not <strong>steam</strong>, I undercut the valve face <strong>and</strong> glued on a viton o-ring. Problem solved.
It’s as <strong>air</strong>tight as a fish now. It’s starting to get exciting now. I spent all morning <strong>build</strong>ing fiddly
little brass parts, but this afternoon I decided to do some "first assembly", as I can't see my friend
who MIGHT have a 0-80 tap <strong>and</strong> drill until he gets home tonight. If I push the end of the "valve
actuator lever" with a screwdriver (to simulate what the 0-80 cam screw will do) the flywheels
take off like a shot, <strong>and</strong> the <strong>engine</strong> bellows like a---like a---well, kind of like a wounded duck!!!
I have never built an <strong>engine</strong> before with such interesting sound effects. Hopefully, after I get the
cam screw in place, <strong>and</strong> get the <strong>engine</strong> timed correctly, it will give more of a "pop" sound rather
than sounding like the offspring of a mad Mallard <strong>and</strong> a Whoopee cushion. Tomorrow I have to
make the arms for the governor <strong>and</strong> solder them to the weights, then try to assemble the
governor---which methinks is too damn much like microsurgery.

I spent the entire day today "frigging" with the flywheel mounted governor.--it works---it
actually works!!! But it takes a heck of a lot of "frigging" with to get it to work. I have test ran it
on my variable speed electric drill, <strong>and</strong> the weight arms do fly out under centrifugal force at mid
range RPMs, <strong>and</strong> the spring does retract them when the drill slows down. Right now the sliding
cam only moves about 0.050", <strong>and</strong> I need it to move about 0.080". It appears that the arms are
hitting on the outer limits of the flywheel clearance holes, limiting the travel. Tomorrow I will
elongate the clearance holes a bit <strong>and</strong> try to squeeze another 0.030" of travel out of the sliding
cam.---I went today <strong>and</strong> bought a #0-80 tap <strong>and</strong> two tap drills---the hole tapping went fine, but
now nobody in Barrie has 0-80 socket head cap screws.

So---We have a runner. I can not get any 0-80 socket head cap screws in Barrie, <strong>and</strong> my "Nut
<strong>and</strong> Bolt store" doesn't seem to be able to order them except in quantities of 50 (at an outrageous
price). If anybody out there would like to take pity on me <strong>and</strong> send me one #0-80 socket head
cup point set screw x 1/8" long, <strong>and</strong> one #0-80 socket head cap screw x 1/8" or 1/4" long, you
would have my everlasting gratitude. See the link to my website for my mailing address. This
morning I got up <strong>and</strong> decided to make a solid cam <strong>and</strong> see if I could get the <strong>engine</strong> to run as a
conventional <strong>engine</strong>, <strong>and</strong> it runs very well as the video shows.---<strong>Brian</strong>
http://s307.photobucket.com/albums/nn294/<strong>Brian</strong><strong>Rupnow</strong>/?action=view&current=Movie_0001.f
lv
..If anybody out there would like to take pity on me <strong>and</strong> send me one #0-80 socket head cup
point set screw x 1/8" long, <strong>and</strong> one #0-80 socket head cap screw x 1/8" or 1/4" long, you would
have my everlasting gratitude...
Well, I've got some 0-80s here, you can have 'em if they'll help ya. Thread length is .180", .237"
OAL. Ignore the short screw, I don't know how it got mixed in with the others.

I just did some quick checking on my CAD mode, <strong>and</strong> it looks like maybe I can use one of the 0-
80 socket head cap screws for a set screw in the valve actuator bushing. It looks like the head
will clear everything ---if so, then its good luck, not good management.
I may have spoken to soon on the governor!! It’s driving me nuts. The weights do fly out from
centrifugal force, <strong>and</strong> move the sliding collar okay. However, when I slow the flywheel down,
the spring doesn't have quite enough strength to return the sliding collar all the way to the low
speed position. This can be fixed by changing to a heavier spring, but then I may have to add a
bit of weight to the counterweights. This is the h<strong>air</strong> pulling part of the <strong>build</strong>, I guess.

I finally got the governor to work the way its supposed to, at least on the variable speed electric
drill. This is a very finicky operation, largely because the pivoting counterweight arms are so
small it is hard to make them with any real accuracy. I also picked up a spray can of International
Red <strong>and</strong> painted the flywheels today. If the 0-80 screws that Vernon sent me get here this week, I
may have a new video to post.
I have had numerous people emailing me <strong>and</strong> asking about the flywheels, <strong>and</strong> if they can <strong>build</strong>
the <strong>engine</strong> as a conventional <strong>engine</strong> without the hit <strong>and</strong> miss function <strong>and</strong> the governors. The
answer is---
#1--The flywheels CAN be made from aluminum, <strong>and</strong> they CAN be made to 1/2" thick. ---<strong>and</strong>
the non governor flywheel does NOT have to have the long extended hub as shown on my
drawing.---I only made the extended hub that long so that both flywheels would be spaced out
the same distance from the crankcase, <strong>and</strong> I wanted the extended hub to drive an o-ring drive
pulley to power some secondary equipment.
#2--You can <strong>build</strong> the <strong>engine</strong> with 2 identical flywheels <strong>and</strong> skip the governors. You will need to
<strong>build</strong> a cam-hub similar to the one in the attached picture.--Please note that I built this from a
"scrap" piece of brass <strong>and</strong> 3/32" steel rod---there is a bit of machining at the extreme outer
diameter of the piece in the picture which serves no purpose <strong>and</strong> doesn't have to be there----And
the one in the drawing will not be as thick as the one I show in the picture

Well boys---Here ya go!!! Its running in hit <strong>and</strong> miss mode. After 2 hours of messing about with
tiny, tiny, tiny #0-80 socket head cap screws <strong>and</strong> adjusting the timing, it runs. This video was
made in the first 5 minutes of operation, so its a bit choppy. It’s been setting on the corner of my
desk running now for half an hour, <strong>and</strong> its getting much smoother. I am happy as a pig in mud!!!
http://s307.photobucket.com/albums/nn294/<strong>Brian</strong><strong>Rupnow</strong>/?action=view&current=HITANDMIS
SWORKING.flv

I may have shot myself in the foot a little by making the flywheels from steel. My theory was
that if the flywheels were uber heavy, they would let the <strong>engine</strong> "coast" longer between firing
cycles. What I overlooked was the fact that since they are so heavy, it takes considerably more
kinetic energy to overcome their "resting inertia", so the <strong>engine</strong> has to fire 5 or 6 times to get the
<strong>engine</strong> spinning fast enough to actuate the governors. If the flywheels had been made of
aluminum, which is 1/3 the weight of steel, the firing profile would probably have been quite
different. When I get back from the Canadian Rod Tour, I am going to <strong>build</strong> a small scale
varying load machine to demonstrate how applied load affects the hit <strong>and</strong> miss cycle as the
<strong>engine</strong> runs.
I have only been machining for about 2 years. Prior to that, I have never ran a mill, <strong>and</strong> only ran
a lathe during my apprenticeship 44 years ago. However, since I have to know what all the shop
machinery is capable of in order to design machinery which is built on lathes, mills, shapers,
etcetera, I had a big head start. There is a world of good information on this website, <strong>and</strong> some
very informative members. One of the really big issues that you will come up against in learning
to machine is knowing what questions to ask. Do a lot of reading, follow the <strong>build</strong>s on this
forum, <strong>and</strong> don't be afraid to ask questions. Go ahead <strong>and</strong> start to <strong>build</strong> something, <strong>and</strong> then
when you are uncertain about what exact method to use to achieve a required result, then you
will know what questions to ask.---And we will help you.—<strong>Brian</strong>
Some folks have been asking me about the springs that I used in this <strong>engine</strong>. ---I just measured
the spring that operates the 1/4" diameter sliding valve inside the cylinder head.---It is 0.19" o.d.
x 0.023" dia. wire x 1.4" free length <strong>and</strong> the pitch is measured at approx. 0.077" . The spring
which keeps the valve in contact with the cam is 0.25" o.d. x 0.023" dia. wire x 1.5" free length
<strong>and</strong> the pitch is approximately 0.1" (Note that in the final <strong>build</strong> of my <strong>engine</strong> I departed from the
blueprints in that area). The spring in the governor is 0.31" o.d. x 0.020" wire x 3/4" free length
x pitch (I've lost that spring--when I disassembled the hit <strong>and</strong> miss valving, to put on a
conventional valve system, the spring escaped <strong>and</strong> was last seen flying under my desk at 300
MPH.)
I was sorting invoices today, when Lo <strong>and</strong> Behold, I came across the paperwork on the three
springs I used on this <strong>engine</strong>. They are identified as #71xINDUS0645655 ----
#74xINDUS0615370 <strong>and</strong> #18xINDUS0615090. They were purchased at Brafasco
(Brampton Fastener Company) which (I believe) is an Ontario based company, but the springs
are probably made in USA.
aermotor8--Seems you are correct---here is a link to their website
http://shop.springsbyajax.com/category.sc?categoryId=2