DETRIOIT DIESEL
Engine Tune-Up
FOUR VALVE CYLINDER HEADS
4.
Loosen the exhaust valve rocker arm 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.
2). 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.
Fig. 2 - Adjusting Valve Clearance (Four-Valve
Cylinder Head)
8.
Check and adjust the remaining exhaust valves,
in the same manner as above.
Cold Engine
Hot Engine
1.
Place the speed control lever in the idle speed
position. If a stop lever is provided, secure it in the no-
Maintaining normal engine operating temperature is
fuel position.
particularly important when making the final valve
clearance adjustment. If the engine is allowed to cool
2.
Remove the loose dirt from the valve rocker
off before setting any of the valves, the clearance, when
cover(s) and remove the cover(s).
running at full load, may become insufficient.
3.
Rotate the crankshaft until the injector follower
1.
With the engine at normal operating
is fully depressed on the cylinder to be adjusted.
temperature (160-185"F.), recheck the exhaust valve
clearance with gage J 9708. At this time, if the valve
CAUTION : If a wrench is used on the crankshaft
clearance is correct, the .023" gage should pass freely
bolt, do not turn the engine in a left-hand direction of
between the end of one valve stem and the rocker arm
rotation as the bolt will be loosened.
bridge and the .025" feeler gage should not. Readjust
the push rod, if necessary.
2.
After the exhaust valve clearance has been
adjusted, check the fuel injector timing.
Page 75
