Service Manual

Valve Stem Diameter
Exhaust 5.440-5.455 (.2142-.2148 in.)
Figure 4-41
3. Calculate the valve stem
to valve guide
clearance wear limit. Subtract the valve
stem diameter from the valve guide
I.D. If
these limits are exceeded, the valves and
valve guides must be replaced.
Intake clearance limit
.08 mm
Exhaust clearance limit ,100 mm
See Valve Guide Replacement on page
30.
4. Valve seat contact is determined by coating
the valve seat with Prussian Blue. Install the
valve and rotate it in its seat. The width of
the contact area for both intake and exhaust
is shown in Fig. 4-42.
Intake and Exhaust Valve Contact Area
,800-1
.OO mm (.0315-.0394 in.)
The pattern must be a continuous ring
without break.
If the pattern is not within
specification, the valve seat must be re-
conditioned
(.0032 in.)
(.0039 in
.)
Valve Seat Contact Pattern
.800-1.00 mm (.0315-.0394 in.)
Figure 4-42
5. Recondition the valve seat. Three cuts are
required to properly recondition the valve
seat. See Fig. 4-43.
The special
tools required are as follows:
“T” handle wrench
50-9480
Adaptor
50-941
0
Expandable Pilot
50-9500
60 Degree Cutter
81-4830
15/45 Degree Cutter 81-4370
30
Valve Seat Angles
15” 45’ 60”
Figure 4-43
A. Install the pilot shaft in the valve guide.
6. Insert the 45 degree cutter and connect
the “T” handle.
C. Cut the seat
to 45 degrees with one or
two turns of the cutter.
D. Coat the seat with Prussian Blue and
measure the contact area on the valve
face. Refer
to step #4 on page 30.
E. If the position of the contact area is low,
see Fig. 4-44A. cut the seat with the 60
degree cutter
to raise the contact area.
F. If the contact area is high, see Fig. 4-
446, cut the seat using the 15 degree
cutter
to lower the contact area.
I “B”
(HIGH)
Figure 4-44 A & B
6. Valve Guide Replacement
The valve guides are shrink-fit in place. Use
the following procedures
to install replace-
ment valve guides.
A. Use valve guide installer and remover,
part number 81-4880,
to drive the old
valve guide out of the head of the engine.
Insert the remover from the combustion
chamber side of the head.
B. Ream the hole with a valve guide reamer,
part number 81-4850. Turn the reamer
with handle. part number 81-4860. The