Refacing Valves; Select Fitting Valves; Camshaft Repair; Crankshaft - Ford VSG-411 Service Manual

l-07
Basic Engine
l-07
seat contacts the face. To do this, coat the seat with Prussian blue
and set the valve in place. Rotate the valve with light pressure. If
the blue is transferred to the center of the valve face, the contact is
satisfactory. If the blue is transferred to the top edge of the valve
face, lower the valve seat. If the blue is transferred to the bottom
edge of the valve face, raise the valve seat.
SEAT WIDTH SCALE
A
FOR DIMENSIONS
CHECK FOR
REFER TO
BENT STEM
SPECIFICATIONS
< DIAMETER
VALVE
VALVE FACE MARGIN
FACE ANGLE
l/32" MINIMUM
(EDGE OF VALVE HEAD)
THIS LINE PARALLEL
WITH VALVE HEAD
I
AlOOSO-1B
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 coordinated
with the valve seat refacing operations 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 aluminum coating and reduce the valves' 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,
alternatively, lap the seats using dummy valves. The exhaust
valves may be lapped in or the faces ground if required.
If the valve face 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 (Figure 1 l), replace the valve as the valve will run
too hot in the engine. 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.
If the valve and/or valve seat has been refaced, it will be
necessary to check the clearance between the rocker arm pad and
the valve stem with the valve train assembly installed in the
engine.
SELECT FllTlNG VALVES
If the valve stem to valve guide clearance exceeds the wear
limit, ream the valve guide for the next oversize valve stem.
Valves with oversize stem diameter ar' e available for service.
Always reface the valve seat after the guide has been reamed.
Refer to Reaming Valve Guides.
FIG. 11 Critical Valve Dimensions
CAMSHAFT REPAIR
Remove light scuffs, scores or nicks from the camshaft ma-
chined surfaces with a smooth oil stone.
CRANKSHAFT
Dress minor scores with an oil stone. If the journals are severely
marred or exceed the wear limit, they should be refinished to size
for the next undersize bearing.
REFINISHING JOURNALS
Refinish the journals to give the proper clearance with the next
undersize bearing. If the journal will not clean up to maximum
undersize bearing available, replace the crankshaft.
Always reproduce the same journal shoulder radius that existed
originally. Too small a radius will result in fatigue failure of the
crankshaft. Too large a radius will result in bearing failure due to
radius ride of the bearing.
After refinishing the journals, chamfer the oil holes; then polish
the journal with a No. 320 grit polishing cloth and engine oil.
Crocus cloth may also be used as a polishing agent.
FITTING MAIN OR CONNECTING ROD BEARINGS
WITH PLASTIGAGE
1. Clean crankshaft journals. Inspect journals and thrust faces
(thrust bearing) for nicks, burrs or bearing pickup that would
cause premature bearing wear. When replacing standard
bearings with new bearings, it is good practice to fit the
bearing to minimum specified clearance. If the desired
clearance cannot be obtained with a standard bearing, try a
0.002 inch undersize in combination with a standard bearing
to obtain the proper clearance.
2. If fitting a main bearing in the chassis, position a jack under
the counterweight adjoining bearing which is being
checked. Support crankshaft with jack so its weight will
not compress Plastigage and provide an erroneous
reading.