3.23
ENGINE
7. Remove valve and check where the Prussian Blueâ„¢
or black marker indicates seat contact on the valve
face. The valve seat should contact the middle of the
valve face or slightly above, and must be the proper
width (A).
• If the indicated seat contact is at the top edge of the
valve face and contacts the margin area(B) it is too
high on the valve face. Use the 30
o
cutter to lower the
valve seat.
• If too low use the 60
o
or 75
o
cutter to raise the seat.
When contact area is centered on the valve face,
measure seat width.
• If the seat is too wide or uneven, use both top and
bottom cutters to narrow the seat.
• If the seat is too narrow, widen using the 45
o
cutter
and re-check contact point on the valve face and seat
width after each cut.
NOTE: When using an interference angle, the seat
contact point on the valve will be very narrow, and is a
normal condition. Look for an even and continuous
contact point on the black marker, all the way around the
valve face.
8. Clean all filings from the area with hot soapy water,
rinse, and dry with compressed air.
9. Lubricate the valve guides with clean engine oil, and
apply oil or water based lapping compound to the face
of the valve. Lapping is not required with an
interference angle.
10. Insert the valve into its respective guide and lap using
a lapping tool or a section of fuel line connected to the
valve stem.
11. Rotate the valve rapidly back and forth until the cut
sounds smooth. Lift the valve slightly off of the seat,
rotate 1/4 turn, and repeat the lapping process. Do this
four to five times until the valve is fully seated, and
repeat process for the other valve.
12. Clean cylinder head, valves, and camshaft oil supply
passages thoroughly.
13. Spray electrical contact cleaner into oil passages and
dry using compressed air.
Proper Seat Contact On Valve Face
(A)
(B)
Bottom 60
o
or 75
o
Top - 30
o
Seat - 45
o
or 46
o
Seat
Width
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