TM 9-2320-260-34-1
3-80. VALVE SEAT GRINDING (Contd)
f. Lapping Valve Seats
1. Apply a light coat of lubricating oil to stem of valve (2) and apply coarse lapping compound to
contact surface of valve (2).
2. Insert valve (2) into cylinder head (1) and lap valve (2) and valve seat (3).
WARNING
Drycleaning solvent is flammable and will not be used near open
flame. Use only in well-ventilated places. Failure to do so may
result in injury to personnel.
3. Remove valve (2) from cylinder head (1) and clean valve (2) and valve seat (3) using a lint-free cloth
and drycleaning solvent.
4. Repeat steps 1 through 3 using fine lapping compound.
5. Apply prussian blue to contact surface of valve seat (3), install valve (2) in cylinder head (1), press
down on valve (2), and rotate back and forth.
NOTE
Contact pattern should be a clear ring of 0.0625-0.125 in.
(1.5875-3. 175 mm).
6. Remove valve (2) and examine valve (2) and valve seat (3) for contact pattern. If contact pattern is
not correct, relap valve(s) (2) and retest (steps 1 through 5).
7. Clean all valves (2) (step 3) and cylinder head (1) (para. 2-8) after all valves (2) and valve seats (3)
have been lapped.
FOLLOW-ON TASK: Assemble cylinder head (para. 3-51).
3-232
