TM 5-3810-300-24&P-3
14.1 Exhaust Valve Clearance Adjustment
ENGINES WITH FOUR VALVE CYLINDER HEADS
The exhaust valve bridges must be adjusted and the
crankshaft in a left-hand direction of rotation or
adjustment screws locked securely at the time the
the bolt may be loosened.
cylinder head is installed on the engine. Until wear
4. Loosen the exhaust valve rocker arm push rod lock
occurs, no further adjustment is required on the exhaust
nut.
valve bridges.
When wear is evident, make the
5. Place a .017 " feeler gage, J 9708, between the end
The exhaust valve clearance is always adjusted at the
of the exhaust valve stem and the valve bridge
push rod. Do not disturb the exhaust valve bridge
adjustment screw (spring-loaded bridge only) or between
adjusting screw.
the valve bridge and the valve rocker arm pallet
(unloaded bridge only) -- refer to Figs. 2 and 3. Adjust
All of the exhaust valves may be adjusted in firing order
the push rod to obtain a smooth pull on the feeler gage.
sequence during one full revolution of the crankshaft.
Refer to the General Specifications at the front of the
6. Remove the feeler gage. Hold the push rod with a
manual for the engine firing order.
5/16 " wrench and tighten the lock nut with a " wrench.
Exhaust Valve Clearance Adjustment (Cold Engine)
7. Recheck the clearance.
At this time, if the
adjustment is correct, the .015 " gage will pass freely
1. Remove the loose dirt from the valve rocker cover
between the valve stem and the adjustment screw
and remove the cover.
(spring-loaded bridge) or between the valve bridge and
the rocker arm pallet (unloaded bridge), but the .017 "
2. Place the governor speed control lever in the idle
gage will not pass through. Readjust the push rod, if
speed position. If a stop lever is provided, secure it in
necessary.
the stop position.
3. Rotate the crankshaft, manually or with the starting
8. Adjust and check the remaining exhaust valves in
motor, until the injector follower is fully depressed on the
the same manner as above.
particular cylinder to be adjusted.
CAUTION: If a wrench is used on the crankshaft
bolt at the front of the engine, do not turn the
Fig. 3 - Adjusting Valve Clearance (Unloaded
Valve Bridge)
Fig. 2 - Adjusting Valve Clearance (Spring-
Loaded Valve Bridge)
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