Figure 4-5. Narrowing valve seat. - TM-5-4320-234-340074

TM 5-4320-234-34

(1) Operate engine until it reaches operating

seat area is corrected, touch the seat lightly with the

temperature.

original grinding stone to remove the burred or

(2) Disconnect

the

positive

crankcase

feathered edge.

ventilation valve and fittings from the valve chamber

cover.

(3) Remove the nuts and washers that secure

the valve chamber cover to the cylinder block. Remove

the valve chamber cover and gasket.

(4) With the engine running at operating

temperature and at idle speed, set the intake valves for

0.014-inch (0.0350 cm) clearance as follows:

(a) Alternately pass a 0.013-inch (0.0325 cm)

and a 0.015-inch (0.0375 cm) flat feeler gage between

the head of the adjusting ,;crew of the tappet (13, fig. 4-

Figure 4-5. Narrowing valve seat.

3) and stem of valve (2).

(b) If a 0.013-inch (0.0325 cm) feeler gage

(11) Inspect the spring retainer seats, spring

moves freely back and forth in gap when the valve is

retaining locks, valve stem caps, and valve tappet

not being lifted, and a 0.0015-inch (0.0375 cm) feeler

assemblies for cracks, scoring, overheating, and wear.

gage binds at all times, the clearance requires no

Replace damaged parts.

adjustment.

d. Installation.

gripped at all times, the clearance is insufficient.

(d) Hold valve lifter with an open end wrench

(1) Position the valve tappet assemblies (13,

while using a second wrench to turn adjusting screw

fig. 4-3) in the engine block.

one-quarter to one-half turn clockwise.

Repeat

(2) Assemble the valves (2 and 7), valve

clearance check and adjustment until you obtain the

springs (5 and 10), spring retainers (4 and 9), valve

proper clearance. The adjustable-type valve lifters have

rotators (3 and 8), and valve locks (1 and 6). Compress

self-locking adjusting screws that require no lock nuts.

the valve springs with a spring compressor to install the

(e) If a 0.015-inch (0.0375 cm) feeler gage

valve locks. Turn the engine over as necessary to allow

moves freely when valve is not being lifted, the

each valve to move to the closed position before

clearance is too great. Hold valve lifter with an open

attempting to install the valve parts. Make sure that you

end wrench while using a second wrench to turn valve

install each valve into the guide from which it was

lifter adjusting screw counterclockwise one-quarter to

removed.

one-half turn.

Repeat the clearance check and

(3) With the engine stopped, temporarily set

adjustment until proper clearance is obtained.

the intake valve-to-tappet clearance to 0.014 inch

(5) Adjust the exhaust valves to a 0.016-inch

(0.0350 cm) and the exhaust valve-to-tappet clearance

(0.0400 cm) (hot) clearance in the manner described

to 0.017 inch (0.0425 cm) (cold).

above, using 0.015 (0.0375 cm) and 0.017 inch (0.0425

(4) Install the cylinder head (para 4-3).

cm) feeler gages.

(5) Operate the engine until it reaches

operating temperature. Adjust valve-to-tappet clearance

4-5. Oil Pan and Filler Blocks

as directed in subparagraph e below.

(6) Install the valve chamber cover (7, fig. 4-

a. Removal.

21).

(1) Remove the drain plug (1, fig. 4-6) and

drain the engine oil into a suitable container. Remove

e. Valve Adjustment.

the oil drain piping (items 2 through 4).

4-8