6-6. MAINTENANCE OF CYLINDER HEAD - (Cont)
adjusting clearance is required
crankshaft, crankcase, or cylinder
if either the cylinder, piston,
head has been replaced.
Inspect clearance of piston and cylinder head as follows:
A plastigage procedure is an option for checking cylinder clearance.
(a) Clean mating surface of cylinder liner.
(b) Install new head gasket.
(c) Use suitable spacers over headstuds and tighten down cylinder to crankcase.
(d) Place piston at TDC.
(e) Using depth gage, measure clearance. Correct clearance is 0.0216-0.0255 inch (0.55-0.65 mm).
Remove and add cylinder head gaskets until proper clearance is obtained.
Measure valve stems. Correct dimension is 0.2740-0.2736 inch (6.995-6.994 mm). Replace valves if
Inspect valve heads for burns, pitting, or signs of blowby. Replace valve if excessive.
Measure rocker shaft diameter. Correct dimension is 0.7084-0.7080 inch (17.983-17.994 mm).
Check rocker radius for flattening. Replace rocker arms if flattened.
Inspect rocker arm bushing for grooves or wear. Replace rocker arm if bushing is worn or grooved.
Check rocker bore diameter. Correct dimension is 0.7096-0.7099 inch (18.024-18.033 mm).
(1) Replace valve guides (44) as follows:
(a) Press out each valve guide (44) with mandrel (Figure 6-10).
(b) Press in new valve guide (44) with mandrel.
(c) Make sure valve guide protrusion on valve guides without collar does not exceed 0.157-0.165 inch
(2) Reface pitted valve seats (45) with a valve seat cutter to a 45 degree angle. Cut until valve seat is
(3) Lap in valves (43) using lapping tool and lapping compound.