WORKSHOP MANUAL - lombardini service

4
Disassembly / Reassembly
91
92
Piston, assembly
Important
Before re-mounting lubrificate the piston pin, piston, cylinder
and conncecting rod big end bearing.
Couple the piston to the connecting rod inserting the pin, after
lubricating it, just via thumb pressure.
Insert the two pin stop rings and check that they are properly
housed in their seats (see fig. 84).
Using piston ring compression pliers, introduce the piston into the
cylinder so that combustion chamber A is directly under the
precombustion chamber parallel to the head.
Couple the piston/connecting rod to the crankshaft.
For tightening the head/connecting rod see fig. 97.
Piston clearance
Determinare the value A of each piston using a dial indicator to
measure the difference between the two surfaces (piston crown and
upper cylinder surface).
To determine the piston clearance and, by consequence, which
copper gaske is most suitable it is necessary to consider the A value
of the piston that projects furthest.
93
Head gasket
94
Important
Remove the cylinder head gasket seal from its protective
covering only when you are going to mount it.
The gasket thickness is identified by the number of notches located
in point B.
Choose the appropriate gasket considering that each A value on
the table corresponds to a gasket with: one hole, two holes, three
holes.
The A value relates to figure 93.
Each time you dismount the head you must replace the gasket.
A (mm)
N° of holes Piston clearance
0.82÷0.91
0.92÷1.01
1 hole
2 holes
0.54÷0.63
1.02÷1.10
3 holes
0.55÷0.63
- 44 - FOCS Workshop Manual_cod. 1.5302.858_1° ed_ rev. 00