Intake and Exhaust Valves - TM-5-4320-258-340039

TM 5-4320-258-34

Cleaning and Inspection.

gradually decreasing toward the ends. Check flatness

lengthwise at each edge and in the middle of the head.

(1) Remove all carbon from combustion

(5) Check flatness crosswise with a

areas with a scraper and wire brush.

Clean all

straightedge and a feeler gage.

The maximum

remaining residue from the cylinder head with cleaning

permissible low spot is 0.003 inch in localized areas.

solvent (FED. Spec. P-D-680). Dry with clean, dry

Check flatness crosswise at each end and between each

compressed air.

combustion chamber.

(2) Clean the top of the cylinder block with

(6) Inspect cylinder head studs for

a scraper and a cloth dampened in cleaning solvent

looseness or damaged threads.

(FED. Spec. P-D-680). Be very careful not to get dirt

(7) Replace the gasket, hoses, and

in the cylinders or water jacket.

defective parts.

(3) Inspect the cylinder head for cracks,

c. Installation. Using a new head gasket,

corrosion, damaged threads, plugged water ports, or

install head in reverse order of removal. Tighten the

other defects.

cylinder head screws in the sequence shown in figure 4-

(4) Check flatness lengthwise with a

2. Torque to 35 to 40 foot-pounds.

straightedge and feeler gage.

The maximum,

permissible low spot is 0.012 inch in the center,

Figure 4-2. Cylinder head cap screw tightening sequence.

4-4.

Intake and Exhaust Valves

Removal.

a. General. The intake and exhaust valves of

(1) Remove the cylinder head (para 4-3).

(2) Remove the valve chamber cover (7,

this L-head engine are mounted in the cylinder block.

fig. 4-22).

They are opened by operation of the camshaft through

(3) Using a spring lifter, compress the

adjustable valve tappets. They are closed by the valve

valve spring (5 or 10, fig. 4-3) at each valve (2 or 7)

springs. The valve stems ride in valve guides which are

and remove the valve locks (1 or 6) from each valve

pressed into the block. The intake valves seat directly

that is in the closed position. Rotate the engine

in the block. The exhaust valve seat in shrink-fit valve

crankshaft to close the remaining valves and remove

seat inserts in the block.

the remaining locks.

4-6