Onan NHC Series Operator's/Service Manual And Parts Catalog page 180

Tappet Adjustment: The engine is 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. Adjust 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
u n t i l the TC 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 its compression stroke, the position
it must be in to get proper valve adjustment for
the left cylinder.
4. Clearances are shown in Dimensions -and Clear-
ances. For each valve, the gauge should just 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 .
^ j r o > a d j u s t valves on the right hand cylinder, turn
engine one complete revolution and again line up
mark on the flywheel and the TC mark on the gear
cover. Then follow adjustment procedure given
for left 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
( S E E T /
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.
, G O V E R N O R CUP
R O L L PIN
ROTATE
GOVERNOR CUP
SO T H A T R O L L PIN
FITS INTO THE
M E T A L L I N E D
H O L E IN T H E CUP.
GOVERNOR ARM
GOVERNOR SHAFT
GOVERNOR
SHAFT YOKE
(Smooth Side
Toward Cup).
OIL SEAL
GOVERNOR
f_ SHAFT
IF FEELER WILL
ENTER HOLE 1/2'
B A L L HAS
F A L L E N OUT
FIGURE 47. GEAR COVER ASSEMBLY
32