Ignition And Battery Charging - Onan NHC Series Operator's/Service Manual And Parts Catalog

IGNITION AND BATTERY CHARGING
B R E A K E R POINTS
To maintain maximum efficiency from the engine,
change the breaker points every 200 hours of operation.
Proceed as follows:
1. Remove the two screws and the cover on the
breaker box.
2. Remove the two spark plugs so engine can be
easily rotated by hand. If plugs have not been
changed within the last lOOhours, replace them
with new ones after setting the breaker points.
3. Refer to Figure 2 1 . Remove mounting screw (A)
and pull the points out of the box just far enough
so screw (B) can be removed and leads discon-
nected.
4. Remove screw (C) and replace condenser with a
new one.
5. Replace points with a new set but do not complete-
ly tighten mounting screw ( A ) .
6. Rotate the engine by hand u n t i l the 25 0 B T C mark
on gear cover aligns with mark on flywheel. Turn
another 1/4 turn ( 9 0 ° ) to ensure points are f u l l y
open.
7. Using a screwdriver inserted i n notch (D) on the
right side of points, turn points until gap measures
. 0 2 0 " with a flat thickness gauge. Tighten mount-
ing screw and recheck gap.
8. Check ignition timing.
The engine is equipped with an. automotive type battery
ignition system. Both spark plugs fire simultaneously,
thus the need for a distributor is eliminated. Spark
advance is set>at 2 5 0 B T C (before top center), and
should be maintained for best engine performance.
Always check timing after replacing ignition points or
if noticing poor engine performance. Proceed as
follows:
Timing Procedure • Engine Running:
1. To accurately check the ignition timing, use a
timing light w i t h engine running at idle speed. Con-
nect the timing light according to its manufacturer's
instructions. Either spark plug can be used as they
fire simultaneously.
2. Start the engine and check the timing. The pointer
on the flywheel should line up with the 2 5 ° mark
on the cover. The timing hole through the f l y w h e e l
and the timing marks on the timing gear cover can
be seen by looking through the flywheel blower
screen. See Figure 25..
NOTE: // timing marks do not line up, readjust
point gap. To advance timing, slightly open gap on
breaker points. To retard timing, slightly close gap
on breaker points. Recheck timing and breaker
point gap after making this adjustment.
MOUNTING SCREWS
Timing Procedure - Engine Not Running: I f a timing
light is not available, check the timing as f o l l o w s :
1. Connect a continuity test lamp set across the
ignition breaker points. Touch one test prod to the
breaker box terminal to which the c o i l lead is
connected and touch the other test prod to a good
ground on the engine.
2. Turn crankshaft against rotation (counterclockwise)
until the points close. Then slowly turn the crank-
shaft with rotation (clockwise).
3. The lamp should go out just as the points break
which is the time at which ignition occurs ( 2 5 0
B T C ) .
FIGURE 2 1 . BREAKER POINT ADJUSTMENT
IGNITION TIMING
The timing on the engine is preset at the factory;-A
non-movable breaker point box is used,.however a slight
timing change could be made by adjusting points.
SPARK PLUGS
Remove both spark plugs and install new ones every
lOOhours. Use Champion N-6 or equivalent. Check to
be sure spark plug gap is set at . 0 2 5 " .
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