DISASSEMBLED CYLINDER HEAD INSPECTION.
Valves. Inspect both the intake and exhaust valves as follows (see Figure 9-3 and Figure 9-4):
Discard any valve if the head is cupped, cracked, or burned. Do not mistake the small, circular
depression in the center of the valve head for cupping.
Discard any valve if the face is pitted or worn to the extent that regrinding would leave rim thickness
(A, Figure 9-3) under 0.105 inch (2.67 mm).
Discard any valve if the stem diameter (B) is under 0.4935 inch (12.535 mm), or rim thickness (A) is
under 0.105 inch (2.67 mm).
Discard any valve if the lock recess is worn to the extent that new locks will not fit securely.
Inspect the valves using fluorescent magnetic particle inspection as follows (see Figure 9-4):
Some valves are of welded construction and have two types of
metal. These valves may be inspected using the fluorescent
magnetic particle method. Due to the change in metal at the weld
area, however, a broad fuzzy leakage pattern will show. To avoid
discarding a serviceable valve, magnetize this type of valve In a
coil at 100 to 200 amperes, remove It from the coil, and apply
fluorescent magnetic particles in suspension. A crack in the weld
area will be indicated by a sharp, bright fluorescent line.
Inspect the valves using fluorescent magnetic particle inspection in accordance with MIL-I-6868.
Magnetize and inspect in two directions using coil shots of 100 to 300 amperes for transverse
defects, and head shots of 500 to 700 amperes for radial defects.
Using a 3-power magnifying glass, inspect each valve in accordance with Figure 9-4.
Discard any valve if magnetic indications in area A are over 0.500 inch (12.70 mm) in length, or
if more than 5 indications spaced closer than 0.125 inch (3.18 mm) are found in area A.
Discard any valve if magnetic indications are found in areas B, C, D, or E.
Repair acceptable valves in accordance with paragraph 9-9.
Valve Springs. Inspect and test the valve springs as follows (see Figure 9-1):
Place the valve spring (3) on a surface plate and check the free length. The valve spring should be
square, and have a free length of approximately 3.349 inches (85.06 mm). Discard valve springs that
are obviously warped or collapsed.
Using valve spring tester 3375182, compress the valve spring to a length of 2.470 inches (62.74 mm),
and note the load needed to compress the spring. Discard springs that are outside the limits of Table
Inspect the valve spring seats (2) for cracks and worn or elongated lock holes. Discard the retainers if
cracked, or if holes are worn or elongated.
Inspect the valve spring guides (4) for cracks. Discard if cracked.
Cylinder Heads. Inspect the cylinder heads as follows (see Figure 9-1, Figure 9-5, Figure 9-6, and Figure 9-
Depending on the equipment available, either an air pressure test,
a water pressure test, or both air and water pressure tests will be
Assemble the head in test fixture ST-1012 using adapter plates 3375070 (3 and 5, Figure 9-5), and
perform an air pressure test as follows: