ARMY TM 9-2815-254-24
AIR FORCE TO 38G1-94-2
(2)
Use a depth gage or straight edge with steel rule to measure valve depression from cylinder head lower
surface.
(3) The standard depression is 0.028 in. (0.7 mm), with a limit of 0.11 in. (2.7 mm). If depression exceeds
limit, replace valve seat insert.
i.
Check valve contact width as follows:
(1) Check valve contact faces for roughness and unevenness. Smooth contact surfaces as necessary.
(2)
Using blue bearing dye (HISPOTBLUE 107), coat valve seat insert. Install valve and rotate valve to pickup
chalk on valve.
(3) Measure valve contact width. Refer to FIGURE 3-70. Standard width is 0.05 to 0.06 in. (1.2 to 1.5 mm),
with a limit of 0.08 in. (2.0 mm).
(4) If measured value exceeds limit, replace valve seat insert.
FIGURE 3-70. Checking Valve Contact Width
j.
Check valve spring free length using a vernier caliper, refer to FIGURE 3-71. Standard height of inner spring
is 1.89 in. (47.9 mm), with a limit of 1.83 in. (46.5 mm). Standard height of outer spring is 1.86 in. (47.3 mm),
with a limit of 1.80 in. (45.8 mm). If measured value is less than limit, replace spring.
k.
Check valve spring inclination using a surface plate and a square. lf inclination measured exceeds 0.04 in.
(1.0 mm), replace spring.
3-119
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