TM 9-4940-549-14&P
(8)
Inspect valve guides for excessive wear. Bore diameter of ex-
haust valve guide shall be 0.3750 to 0.3790 inch. Bore diame-
ter of intake valve guide shall be 0.3740 to 0.3780 inch.
Replace worn valve guides as follows:
(9)
(a) Use a 5/8-inch drift with a 3/8-inch pilot and drive out
valve guides.
(b) Drive replacement valve guides to depth of 1.3700 to 1.3800
inches below cylinder head deck.
(c) Ream bore diameter of intake valve guides to 0.3740 to
0.3750 inch.
(d) Ream bore diameter of exhaust valve guides to 0.3750 to
0.3760 inch.
(10)
Inspect valve springs for cracks, breaks, and distortion. Using
a spring tester, compress valve spring to a length of 1.4920
inches. Test load shall be 72 to 82 pounds. Compress spring
to a length of 1.0820 inches. Test load shall be 80 to 86
pounds.
Inspect cylinder head for cracks, breaks, and broken studs.
(11)
Remove broken studs by center punching, drilling, and using
an easy out.
Check cylinder head for warpage using a straight edge and
(12)
feeler gauge. Check lengthwise and between each cylinder
crosswise. Warpage shall not exceed 0.003 inch laterally and
0.005 inch longitudinally. Cylinder head may be milled to re-
move minor warpage.
Perform magnetic particle inspection in accordance with estab-
(13)
lished procedures.
(14)
Inspect valve seats of cylinder head. If they are pitted or if
new valve guides were installed, the valve seats must be refin-
ished, using a tool with a 3/8-inch pilot. Both intake and ex-
haust valve seats should be refinished on an angle of 30 degrees
for intake valves and 45 degrees for exhaust valves.
NOTE
Use a vibrating angle grinder type
tool. The large diameter and sur-
face area of the valve seats makes
obtaining a proper finish with a
reamer type tool extremely difficult.
Inspect valve for bent or broken stems, cracks, and pitting of
(15)
sealing surface. Using a micrometer, check valve stem diameter
to determine wear. Stem diameter of intake valves shall be
12-14
