14.1 Exhaust Valve Clearance Adjustment
DETROIT DIESEL 53
4. Loosen the push rod lock nut.
5. Place a .027 " feeler gage, J 9708, between the end
of one valve stem and the rocker arm bridge (Fig. 1).
Adjust the push rod to obtain a smooth pull on the feeler
gage.
6. Remove the feeler gage. Hold the push rod with a
5/16 " wrench and tighten the lock nut with a 1/2"
wrench.
7. Recheck the clearance.
At this time, if the
adjustment is correct, the .025 " gage will pass freely
between the end of one valve stem and the rocker arm
bridge and the .027" gage will not pass through.
Readjust the push rod if necessary.
Exhaust Valve Clearance Adjustment (Hot Engine)
Fig. 1. - Adjusting Valve Clearance (Four Valve
Normal engine operating temperature is particularly
Head)
important when making the final valve clearance
adjustment. If the engine is allowed to cool off before
Exhaust Valve Clearance Adjustment (Cold Engine)
setting any of the valves, the clearance, when running at
full load, may become insufficient.
1.
Clean the loose dirt from the exterior or the
engine and remove the valve rocker cover(s).
With the engine at normal operating temperature (160 -
185 F.), recheck the exhaust valve clearance with
2.
Place the speed control lever in the idle speed
feeler gage J 9708. At this time, if the valve clearance
position. If a stop lever is provided, secure it in the no-
is correct, the .023 " gage should pass freely between
fuel position.
the end of one valve stem and the rocker arm bridge
and the .025 " feeler gage should not. Readjust the
3.
Rotate the crankshaft, manually or with the
push rod, if necessary.
starting motor, until the injector follower is fully
depressed on the cylinder to be adjusted.
Use new gaskets when installing the valve rocker
cover(s).
CAUTION: If a wrench is used on the crankshaft
bolt, do not turn the engine in a left-hand
direction of rotation or the bolt will be loosened.
1972 General Motors Corp.
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