TM 10-4320-310-14
6-2.
REPAIR CYLINDER HEAD AND VALVE ASSEMBLY (Continued)
5
The cylinder contact surface of the cylinder head can be repaired by machining. Remove up to a maximum of
0.0196 inch (0.5 mm) of metal provided the minimum valve recession is maintained.
6
Replace any valves that show head warping, burning, or other damage.
7
Replace valves that have seriously scratched or scuffed stems, or pitted, ridged, or cracked tulips, faces, or heads.
8
Replace valves that have a valve head diameter of less than 1.200 inch (30.5 mm).
9
Remove slight scratches or scuff marks.
10
If the cylinder head valve seats were recut, lap the valves by using valve reseating tool and 600 grit lapping and
grinding compound.
The valve recession must not be less than 0.018 inch (0.45 mm), otherwise
valve head may touch piston.
11
After lapping valves, check valve recession.
The valve recession shall be a maximum of 0.036 inch (0.90 mm) and a minimum of 0.018 inch (0.45 mm).
TEST:
1
Insert valve (1) into cylinder head (2).
2
Install cap (3) over valve (1) stem.
3
Install washer (4) on cap (3).
4
Install spring (5) on washer (4).
5
Insert cup (6) into spring (5).
6
Install two collet halves (7) into cup (6) and over
valve (1) stem.
7
Press down on collet halves (7) and cup (6) until
spring (5) compress and collet halves (7) are locked
in slot in valve (1) stem.
6-4
