EXHAUST VALVE CLEARANCE ADJUSTMENT
The correct exhaust valve clearance at normal engine
3. Rotate the crankshaft, manually or with the starting
operating temperature is important for smooth, efficient
motor, until the injector follower is fully depressed on the
operation of the engine.
particular cylinder to be adjusted.
Insufficient valve clearance can result in loss of
NOTE: If a wrench is used on the
compression, misfiring cylinders and, eventually, burned
crankshaft bolt at the front of the
valve seats and valve seat inserts. Excessive valve
engine. do not turn the crankshaft in
clearance will result in noisy operation, increased valve
a left-hand direction of rotation
face wear and valve lock damage.
because the bolt may loosen.
Whenever the cylinder head is overhauled, the exhaust
4. Loosen the exhaust valve rocker arm push rod
valves are reconditioned or replaced, or the valve
operating mechanism is replaced or disturbed in any
way, the valve clearance must first be adjusted to the
5. Place a .012" i.004" feeler gage (J 9708-01) between
cold setting to allow for normal expansion of the engine
the exhaust valve stem and the rocker arm (Fig. I).
parts during the engine warm-up period. This will
Adjust the push rod to obtain a smooth pull on the feeler
ensure a valve setting that is close enough to the
specified, clearance to prevent damage to the valves
when the engine is started.
6. Remove the feeler gage. Hold the push rod with a
5/16" wrench and tighten the locknut with a 1/2" wrench.
All of the exhaust valves may be adjusted in firing order
sequence during one full revolution of' the crankshaft.
Recheck the clearance.
At this time, if the
Refer to the General Specifications at the front of the
adjustment is correct, the .011" feeler gage will pass
manual for the engine firing order.
freely between the valve stem and the rocker arm, but
the .013" feeler gage will not pass through. Readjust the
Valve Clearance Adjustment (Cold Engine) 100°F
push rod, if necessary.
(38°C) or less
8. Check and adjust the remaining exhaust valves in
1. Remove the loose dirt from the valve rocker cover
the same manner as outlined above.
and remove the cover.
Valve Clearance Adjustment (Hot Engine)
2. Place the governor speed control lever in the idle
Maintaining normal engine operating temperature is
speed position. If a stop lever is provided, secure it in
particularly important when making the final exhaust
the stop position.
valve clearance adjustment. If the engine is allowed to
cool before setting any of the valves. the clearance,
when running at full load, may become insufficient.
1. With the engine at normal operating temperature
clearance with feeler gage J 9708-01. At this time, if the
valve clearance is correct, the .008" feeler gage will
pass freely between the end of the valve stem and the
rocker arm and the .010" gage will not pass through.
Readjust the push rod, if necessary.
2. After the exhaust valve clearance has been adjusted,
Fig. 1 - Adjusting Valve Clearance (Two Valve Head)