2-21. CYLINDER HEAD AND VALVE REPAIR (Contd)
1. Using bench grinder and rotary wheel wire brush, clean all valve stems (2) and valve heads (3).
2. Using drill motor and rotary end wire brush, clean all combustion chambers ( 12) and intake and
exhaust ports (13).
3. Refer to para. 2-9 for additional cleaning information.
4. Repeat steps 1 through 3 for opposite cylinder head.
For general inspection instructions, refer to para. 2-10.
Inspect valves (1) for cracks, scoring, galling, and burned heads (3). Replace valves (1) if cracked,
scored, galled, or if heads (3) are burned.
Inspect valve springs (8) and dampers (7) for damage. Replace valve spring (8) if either are
Inspect valve caps (5), shields (6), valve spring shims (9), and valve keys (4) for damage. Replace
Remove dampers (7) from valve springs (8). Using valve spring tester, compress valve spring (8)
to 1-13/16 in. (46 mm). If pressure is less than 70 lb (311 N), replace valve spring (8). Compress
valve spring (8) to 1-25/64 in. (35 mm). If pressure is less than 220 lb (978 N), replace valve
spring (8). Test remaining springs in same manner. Install dampers (7) into springs (8).
Inspect cylinder head (11) for cracks in valve ports (13) or combustion chambers (12) and external
cracks to the coolant chamber (14). Replace cylinder head (11) if cracked.
Precombustion chamber is available in standard and oversize.
If replacing a precombustion chamber, check for marking "OS
on precombustion chamber. If marking is present, oversize pre-
combustion chamber must be used.
Inspect precombustion chambers (10) for cracks or damage. Replace if cracked or damaged.
Inspect cylinder head (11) mating surfaces for scratches or dents. Replace cylinder head (11) if
scratched or dented deeper than 0.003 in. (0.076 mm).
Using a straight edge and feeler gauge, check flatness of cylinder head to block mating surface.
Flatness of cylinder head (11) must not vary more than 0.002-in. (0.051 mm) in distance of 6 in.
(15.2 cm), or more than 0.006 in. (0.152 mm) overall. Replace cylinder head (11) if flatness does not