ARMY TM 9-2815-259-24
AIR FORCE TO 38G1-125-2
MARINE CORPS 09249A/09246A-24
(2) Compare valve recess measurements for all valves to specifications given in Table 4-4. Install
new valves, inserts, or grind existing valves and inserts, as necessary, to obtain proper valve
Table 4-4. Valve Recess Specifications
Intake Valves (new or rebuilt)
0.024 - 0.044 in. (0.61 - 1.11 mm)
Intake Valves (worn)
0.024 - 0.064 in. (0.61 - 1.63 mm)
Exhaust Valves (new or rebuilt)
0.048 - 0.068 in. (1.22 - 1.72 mm)
Exhaust Valves (worn)
0.048 - 0.089 in. (1.22 - 2.26 mm)
(3) If valve recess is not within specifications, install new valves or valve seat inserts, or grind
existing valves and valve seat inserts, to obtain proper valve recess.
c. Testing Prior to Installation.
(1) Clean and inspect cylinder head cap screws as follows:
Cleaning solvent is flammable and toxic to eyes, skin, and respiratory tract.
Skin and eye protection are required. Avoid repeated/prolonged contact.
Provide adequate ventilation. Failure to comply could result in serious
injury or death.
Compressed air used for cleaning can create airborne particles that may
enter the eyes. Never exceed 30 psi (207 kPa) of pressure. Eye protection
required. Failure to comply could result in serious eye damage or
(a) Clean entire length of cap screws. Use wire brush and solvent to remove rust and scale.
Dry cap screws with compressed air.
(b) Inspect cap screws for corrosion damage and overall condition of threads. Cap screws
with corrosion or other imperfections must be replaced.
(2) Clean and inspect top deck of cylinder block as follows:
(a) Remove gasket material, rust, carbon, and other foreign material from top deck of cylinder
block. Gasket surface must be clean.
(b) Clean threaded holes in cylinder block using 2-13 UNC-2A tap about 3.0 in. (76 mm) long.
Use compressed air to remove debris and fluids from cap screw holes. Replace block if
there is evidence of damage.