Service Manual

2-10 PERIODIC MAINTENANCE
Periodic Maintenance Procedures
Marks Stamped on the Cutter:
The marks stamped on the back of the cutter represent the following.
1 Cutter number, selected from 1 to 12
30

Cutter angle [A]
37.5 Cutter diameter of cutter [B]
KS8B Manufactured lot number
Operating Procedures:
•
Clean the seat area carefully.
•
Recondition the valve seats with the valve seat cutters (45

,32

) and
lap the valves.
•
Check the seats for good contact all the way around with machinist’s
dye.
•
Measure the seat width [A]. If it is more than the STD width, the
seating surface should be refaced.
•
If the valve seating pattern is not correct, repair the seat.
•
Coat the seat with machinist’s dye.
•
Fit a 45

cutter [A] to the holder and slide it into the valve guide.

Resurface the valve seat with a 45

cutter, removing only enough
material to produce a smooth and concentric seat.
CAUTION
Do not grind the seat too much. Overgrinding will reduce
valve clearance by sinking the valve into the head. If the valve
sinks too far into the head, it will be impossible to adjust the
clearance, and the cylinder head must be replaced. Do not
turn the cutter counterclockwise or drop it against the seat, or
it will be dulled.
•
Use a 32

seat cutter [A] to narrow the seat width to the STD width.

Turn the seat cutter one turn at a time while pressing down very lightly.
Check the seat width after each turn.
CAUTION
The 32

cutter removes material very quickly. Check the seat
width frequently to prevent over grinding.
NOTE

Keep the seat width as close as possible to the STD width.
•
Make a light pass with the 45

cutter to remove any possible burrs at
the edge of the seat.
•
After resurfacing the seat, inspect for even valve seating.

Apply a machinist’s dye to the valve face, insert the valve, and snap it
closed against the seat several times. The valve surface should show
good contact all the way around. Be sure the valve seat is centered
on the valve face. The position of the valve in the seat is evident after
lapping the valve.
If the seat does not make proper contact, lap the valve into seat with
a vacuum cap tool.