Onan NHC Series Operator's/Service Manual And Parts Catalog page 117

Tappet Adjustment: The ehgine i s equipped with ad-
justable valve tappets. The valve tappet clearance
should be checked and adjusted, i f necessary, at least
every 400 operating hours or when poor engine perform-
ance is noticed. A d j u s t the valve clearance only when
engine is at ambient temperature. Proceed as follows:
1. Remove a l l parts necessary to gain access to
valve tappets.
2. Remove spark plugs to make turning the engine,
easier.
3. Use the engine flywheel to turn the engine over
slowly by hand u n t i l the l e f t hand intake valve
opens and closes. Continue turning the flywheel
until the T C mark is on the top and: lined up with
the T C mark on the gear cover. Both valves should
be closed. T h i s should place the left hand piston
at the top of i t s compression stroke, the position
i t must be i n to get proper valve adjustment for
the l e f t cylinder.
4. Clearances are shown i n Dimensions and Clear-
ances. For each valve, the gauge should j u s t pass
between the valve stem and valve tappet.
5. T o correct the valve clearance, turn the adjusting
screw as needed to obtain the right clearance. The
screw is s e l f - l o c k i n g .
6. To adjust valves on the right hand cylinder, turn
engine one complete revolution and again line up
mark on the f l y w h e e l and the TC mark on the gear
» cover. Then f o l l o w adjustment procedure given
for l e f t hand cylinder.
7. Replace a l l parts removed. Tighten a l l screws
securely. Torque manifold b o l t s .
I N T A K E A N D E X H A U S T V A L V E S
(SEE T A B L E O F C L E A R A N C E S )
FIGURE 46. V A L V E ADJUSTMENT
FLYWHEEL
Use a suitable puller (with claws or with bolts to agree
with flywheel) to pull the flywheel.
Do not drop the flywheel. A broken f i n w i l l destroy
the balance. Always use a steel key for mounting
the flywheel. •
GOVERNOR CUP
ROLL PIN
ROTATE
GOVERNOR CUP
SO T H A T ROLL PIN
FITS INTO T H E
M E T A L LINED
HOLE IN T H E CUP.
GOVERNOR ARM
GOVERNOR SHAFT
GOVERNOR
SHAFT YOKE
(Smooth Side
Toward Cup)
OIL SEAL
GOVERNOR
L SHAFT
IF F E E L E R WILL
ENTER HOLE l ^ "
B A L L HAS
F A L L E N OUT
FIGURE 47. GEAR COVER ASSEMBLY
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