Engine Tune-Up
DETROIT DIESEL
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 / 1 6 " 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.
8. Check and adjust the remaining exhaust valves, in
Fig. 2 - Adjusting Valve Clearance (Four-Valve
the same manner as above.
Cylinder Head)
Cold Engine
Hot Engine
Maintaining normal engine operating temperature is
1. Place the speed control lever in the idle speed
particularly important when making the final valve
position. If a stop lever is provided, secure it in the no-
clearance adjustment. If the engine is allowed to cool
fuel position.
off before setting any of the valves, the clearance,
when running at full load, may become insufficient.
2. Remove the loose dirt from the valve rocker cover(s)
and remove the cover(s).
1. With the engine at normal operating temperature
(160-185F or 71-85C), recheck the exhaust valve
clearance with gage J 9708. At this time, if the valve
3. Rotate the crankshaft until the injector follower is
clearance is correct, the .023" gage should pass freely
fully depressed on the cylinder to be adjusted.
between the end of one valve stem and the rocker arm
bridge and the .025" feeler gage should not. Readjust
CAUTION: If a wrench is used on the crankshaft
the push rod, if necessary.
bolt, do not turn the engine in a left-hand
d i r e c t i o n of rotation as the bolt will be
2. After the exhaust valve clearance has been adjusted,
loosened.
check the fuel injector timing.
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