Measure the outside diameter of the seating surface with a vernier
If the outside diameter of the seating surface is too small, repeat the
grind until the diameter is within the speciﬁed range.
If the outside diameter of the seating surface is too large, make the
grind described below.
If the outside diameter of the seating surface is within the speciﬁed
range, measure the seat width as described below.
Grind the seat at a 32
angle until the seat O.D. is within the speciﬁed
To make the 32
grind, ﬁt a 32
the valve guide.
Turn the holder one turn at a time while pressing down very lightly.
Check the seat after each turn.
cutter removes material very quickly. Check the seat
outside diameter frequently to prevent overgrinding.
After making the 32
grind, return to the seat O.D. measurement step
To measure the seat width, use a vernier calipers to measure the
width of the 45
angle portion of the seat at several places around
If the seat width is too narrow, repeat the 45
slightly too width, and then return to the seat O.D. measurement step
If the seat width is too wide, make the 60
If the seat width is within the speciﬁed range, lap the valve to the seat
as described below.
Grind the seat at a 60
angle until the seat width is within the speciﬁed
To make the 60
grind, ﬁt 60
Turn the holder, while pressing down lightly.
After making the 60
grind, return to the seat width measurement step
Lap the valve to the seat using a lapper, once the seat width and O.D.
are within the ranges speciﬁed above.
Put a little coarse grinding compound on the face of the valve in a
number of places around the valve head.
Spin the valve against the seat until the grinding compound produces
a smooth, matched surface on both the seat and the valve.
Repeat the process with ﬁne grinding compound.
[B] Valve Seat
The seating area should be marked about in the middle of the valve
If the seat area is incorrect place on the valve, be sure to check the
valve is the correct part. If it is, it may have been refaced too much
replace the valve.
Be sure to remove all grinding compound before assembly.
When the engine is assembled, be sure to adjust the valve clearance
(see Valve Clearance Adjustment).
cutter to the holder, and slide it into
grind until the seat is
grind described below.
cutter to the holder, and slide it into the
ENGINE TOP END 4-23