Service Manual

Inspection/Service
Valve Seat Width:
Clean the valve seat surface. Measure the valve
seat width. Apply red lead to the valve surface to
check for scratches and unevenness.
If the meas-
urement is within that specified in
Dimensions and
Clearances,
check the seating ratio. If the ratio is
less than
70%, refit it. If the measurement is not as
specified in
Dimensions and Clearances, replace
the cylinder head and valve and refit the valve seat.
Valve Seat Cuffing:
Refer to Figures 11-9 and 11-10. Clean the valve
seat up by using a
45O valve seat cutter. Replace the
valve and visually check the contact position
be-
tween the valve face and seat with red lead. Cut the
upper surface
of the valve seat with a 15" valve seat
cutter until the valve seat touches to the center
of
the valve face (A should equal Bas shown in Figure
11-10). Cut the valve seat again with the 45" valve
seat cutter and recheck the contact between the
valve and seat. Repeat the last
two steps until the
correct, contact is achieved. Lap valve until the
seated rate becomes more than
70% of the total
contact area.
I
15"
FIGURE 11-9. VALVE SEAT CUTTER
45"
VT-1049
FIGURE 11-10. VALVE SEAT CONTACT
11-7