Onan CCK Service Manual

Each timing gear is stamped with an 0 mark nearthe
edge. The gear teeth must mesh so that these marks
coincide exactly when the gears are installed in the
engine, Figure 62. Be sure, when installing the
camshaft gear and shaft assembly, that the thrust
washer is properly in place behind the camshaft gear.
Replace the camshaft retaining washer and lock ring
to the crankshaft.
CYLINDER HEADS
The cylinder head should be tightened in the order
designated per Fig ure 63 to a torq ue of 5foot-pounds,
then 10 foot-pounds, etc., until all are torqued to 29 to
31 foot-pounds (7 then 14, 21, to 39-42 N*m).
Do not remove heads when they are
i hot. Warpage may occur.
FIGURE 63. HEAD BOLT TIGHTENING
SEQUENCE
VALVES
Properly seated valves are essential to good engine
performance. The cylinder head is removable for
valve servicing. Do not use a pry to loosen the cylinder
head. Rap sharply on the edge with a soft-faced
hammer, taking care not to break any cooling fins. A
conventional type valve spring lifter may be used
when removing the valve spring locks, which are of
the split type. Clean all carbon deposits from the
cylinder head, piston top, valves, guides, etc. If a valve
face is burned or warped, or the stem worn, install a
new valve.
An optional valve stem seal is used on the intake valve
guides of some engines. This seal must be replaced
each time the valve is removed.
Worn valve stem guides may be replaced from inside
the valve chamber. See Figure 64. A seal is provided
behind the intake valve guides only. The smaller
diameter of the tapered valve guides must face toward
the valve head.
Tappets are also replaceable from the valve chamber,
after first removing the valve assemblies.
The valve face angle is 44 degrees. The valve seat angle
is 45 degrees. This 1-degree interference angle
results in a sharp seating surface between the valve
and the top of the valve seat The interference angle
method of grinding valves minimizes face deposits
and lengthens valve life, Figure 65.
The valves should not be hand lapped, if at all
avoidable, since the sharp contact may be destroyed.
This is especially important where stellite faced
valves and seats are used. Valve faces should be
finished in a machine to 44 degrees. Valve seats
should be ground with a 45 degree stone and the
width of the seat band should be 1/32 to 3/64 of an
inch (0.79 to 1.2 mm) wide. Grind only enough to
assure proper seating.
Remove all grinding compound from engine parts
and place each valve in its proper location. Check
each valve for a tight seat, using an air pressure type
testing tool. If such a tool is not available, make pencil
NOTE USE A STANDARD AUTOMOTIVE TYPE
WRENCH TO ADJUST THE TAPPETS.
.rir^
VALVE SEAT '
INSERT;
VALVE :
VALVE CLEARANCE
ti
VALVE ADJUSTING
' SCREW
VALVE RETAINER-
VALVE SPRING^
VALVE GUIDE,
VALVE SPRING
WASHER LOCK
\ VALVE
a Sg
\ crfT
'JOp’ (INTAKE VALVE
X STEM
am!
\— ^j\v-
* 1 ONLY)
SEAL
(OPTIONAL)
VALVE ROTATOR
vr-iws
. FIGURE 64. VALVE ASSEMBLY

Onan CCK Specifications

General

Cylinders	2
Ignition System	Battery ignition
Fuel Type	Gasoline
Cooling System	Air-cooled
Fuel System	Carburetor
Starter	Electric
Governor	Mechanical
Max RPM	1800 RPM
Engine Type	4-cycle
Bore and Stroke	3.25 x 3.625 inches (82.55 x 92.08 mm)