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TM 5-2420-222-34
3-12.
VALVE MAINTENANCE (Con’t).
4.
Inspect valve, valve spring, valve lock, exhaust valve cap, and valve seat for cracks, breaks, scoring, and excessive
wear. Replace defective parts.
5.
Using micrometer caliper set, measure outside diameter of valve head. Outside diameter for intake valve must be
1.767-1.777 in. (44.882-45.136 mm). Outside diameter for exhaust valve must be 1.570-1.580 in. (39.878-40.132
mm).
6.
Using micrometer caliper set, measure length of valve. Length must be 5.1340-5.1740 in. (130.4036-131.4196 mm).
7.
Using micrometer caliper set, measure diameter of valve stem. Refer to Table 3-2 for valve stem diameter
specifications.
8.
Using telescoping gage set and vernier caliper, measure inside diameter of valve guide in cylinder head. Refer to
Table 3-2 for valve guide diameter specifications.
9.
Subtract measurement taken in step 7 from measurement taken in step 8. The difference is valve stem-to-guide
clearance. Clearance must be 0.0020-0.0060 in. (0.0508-0.1524 mm).
Table 3-2. Valve Guide and Stem Diameter Specifications.
Valve Stem Type
Valve Guide Diameter
Valve Stem Diameter
(Inches)
In Inches (mm)
In Inches (mm)
Standard
0.3745-0.3765
0.3715-0.3725
(9.5123-9.5631)
(9.4361-9.4615)
0.003 Oversize
0.3748-0.3768
0.3718-0.3728
(9.5199-9.5707)
(9.4437-9.4691)
0.015 Oversize
0.3760-0.3780
0.3730-0.3740
(9.5504-9.6012)
(9.4742-9.4996)
0.030 Oversize
0.3775-0.3795
0.3745-0.3755
(9.5885-9.6393)
(9.5123-9.5377)
10. Using spring tester and torque wrench, compress valve spring to 1.8125 in. (46.0375 mm) and note compression
force on torque wrench. Compression force must be 54-62 lb.-ft. (73-84 N•m).
11. Using spring tester and torque wrench, compress valve spring to 1.3594 in. (34.5288 mm) and note compression
force on torque wrench. Compression force must be 133-153 lb.-ft. (180-207 N•m).
12. Position valve in place in cylinder head. Using micrometer depth gage, measure distance from cylinder head deck to
valve. Distance must be 0.023-0.047 in. (0.584-1.194 mm) for intake valve and 0.038-0.072 in. (0.965-1.829 mm) for
exhaust valve.
13. Remove valve from cylinder head. Apply thin coat of Prussian blue dye to valve face. Position valve In place in
cylinder head.
14. Turn valve one complete revolution, then remove valve from cylinder head.
15. Inspect valve for low spots or evidence of poor contact between valve and cylinder head. Low spots will be free of
Prussian blue dye. If contact is poor, repair cylinder head (see paragraph 3-6) and valve as required.
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