l-22
BASIC ENGINE
I-22
OVERHAUL (Continued)
VALVES
Minor pits, grooves, etc., may be removed.
Discard valves that are severely damaged, if the
face runout cannot be corrected by refinishing or
stem clearance exceeds specifications.
Discard
any excessively worn or damaged valve train
parts.
REFACING VALVES
The valve refacing operation should be closely
VALVE TYPICAL,
FOR DIMENSIONS REFER
-DIAMETER
TO SPECIFICATIONS
coordinated with the valve seat refacing opera-
tions so that the finished angles of the valve face
and of the valve seat will be to specifications
and provide a compression-tight fit. Be sure that
the refacer grinding wheels are properly
dressed.
Under no circumstances should the faces of
aluminized intake valves be ground or the valves
lapped in as this will remove the diffused alumi-
num coating and reduce the valve’s wear and
heat resistant properties. If the valve faces are
worn or pitted it will be necessary to install new
valves and to resurface the valve seats or, alter-
natively, lap the seats using dummy valves. The
exhaust valves may be lapped in or the faces
ground if required.
If the valveiace runout is excessive and/or to
remove pits and grooves, reface the valves to a
true 44 degree angle. Remove only enough
stock to correct the runout or to clean up the pits
and grooves. If the edge of the valve head is
less than l/32 inch thick after grinding, replace
the valve as the valve will run too hot in the en-
gine.
The interference fit of the valve and seat
should not be lapped out. Remove all
grooves or score marks from the end of the
valve stem, and chamfer it as necessary. Do
not remove more than 0.010 inch from the
end of the valve stem.
VALVE FACE ANGLE
THIS LINE PARALLEL
WITH VALVE HEAD
f
A6803-B
If the valve and/or valve seat has been re-
faced, it will be necessary to check the
clearance between the rocker arm pad and the
valve stem with the valve train assembly in-
stalled in the engine.
SELECT FITTING VALVES
If the valve stem to valve guide clearance ex-
ceeds the wear limit, ream the valve guide for
the
next
oversize valve stem. Valves with over-
size stem diameters of 0.003, 0.015 and 0.030
inch are available for service.
Always reface
the valve seat after the valve guide has been
reamed. Refer to Reaming Valve Guides.
CAMSHAFT REPAIR
Remove light scuffs, scores or nicks from the
camshaft machined surfaces with a smooth oil
stone.
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