TM 9-4520-251-14
5-13 VALVES AND TAPPETS (CONT)
Location/Item
Action
Remarks
INSPECTION
1 .
Valves and
seats
2.
Dimension
checks
Inspect exhaust valve (1), seat (2), intake valve (3),
and seat (4) for cracks, burns, and deposits.
Rotate crankshaft until
each valve is open and
measure seat angles and
surface dimensions.
Width of valve seat (5)
should be 3/64 to 1/16
inch (1.19 to 1.58 mm).
Seat angle of exhaust
valve (1) must be 45°,
and seat angle of intake valve (3) must be 30°. Valve margin (6)
should be more than 1/64 inch (0.4 mm). If valve is defective,
badly burned, or does not meet these measurements, forward to
generaI support maintenance for repair or replacement.
5-29
