ARMY TM 9-2815-259-24
AIR FORCE TO 38G1-125-2
MARINE CORPS 09249A/09246A-24
Support weight of grinder to avoid excessive pressure on grinding stone.
Failure to comply could result in damage to valve seat.
Do not grind valve seat too long. Only a few seconds are required to
recondition the average valve seat. Avoid tendency to grind off too much.
Do not apply excessive pressure. Failure to comply could result in damage
to valve seat.
While applying light pressure, carefully grind valve seat with grinding stone.
Remove arbor, grinding stone, and pilot from valve seat.
If valve seat width is too narrow, valve may burn or erode. Use care when
narrowing valve seat width.
Check valve seat width with vernier caliper. Valve seat width should be 0.059 -
0.079 in. (1.50 - 2.00 mm). If valve seat is too wide, reduce width by repeating
steps 1 through 5 using a 45° grinding stone.
Position new or refaced valve in cylinder head and check contact between valve
seat and valve face using blue bearing dye. If necessary, lap valve onto valve
seat using a lapping tool and lapping compound. Replace valves and valve
inserts as necessary.
Check valve recess in cylinder head, refer to step 4.7.4.(b).
It is not necessary to replace valve seat inserts if valve seats were
Replace valve seat inserts as follows:
Do not use oxygen-acetylene torch to remove valve seat inserts. Oxygen-
acetylene torch will alter the hardness of cylinder head and could cause
damage to engine.
Raise a burr on bottom of valve seat insert.
Protect surface of cylinder head with cardboard or cloth.