Onan MJA Series Service Manual page 50

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Dirty points can be cleaned with tape
and carbon tetr achloride. But if the
points are excessively pitted, they
must be replaced.
3.3.4.2 Timing. - Ignition timing
means adjusting the dsitributor so
the spark for each cylinder fires at
the correct time for maximum power
(25
0
BTC of each compression
stroke).
The MJC ignition system may be
timed either with the engine stopped
, - ' ; ' 9 1 '
or running. But before timing the -
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ignition, be sure both sets of break- FIG 3.3. I - MEASURING DISTRIBUTOR
er points are clean and properly ad- BREAKER GAP
justed. Breaker point set no. 1
opens to fire cylinders 1 and 4 while point set no. 2 opens to fire cylin­
ders 2 and 3.
A. Timing Procedure, Engine Stopped.
1.
Disconnect the low voltage lead to the distributor and connect a test
lamp and battery so the lamp lights when the no. 1 set of breaker
points are closed.
2. Remove the spark plug from #1 cylinder and rotate the flywheel
clockwise until air is forced out of the spark plug hole.
3. Continue rotating the flywheel slowly until the test lamp goes out,
indicating that the breaker points have opened. This is the ignition
point. If the TC mark on the flywheel and the ignition timing pointer
are aligned, timing is correct, otherwise the distributor will have
to be adjusted.
4. To correct timing, align the flywheel TC mark and the timing point­
er. Then loosen the distributor body and rotate it (clockwise if igni ­
tion occurred early and counterclockwise
if
late), until the light goes
out.
5. Retighten the distributor body in the new position and recheck the
timing, step 3. If timing still doesn't occur at the correct point, re ­
peat step 4.
6. The no. 2 set of points should be properly timed to open if the gap is
correct (.017 - .022 in.) and no . 1 set of points has been properly
adJusted. However, they may be checked for proper timing by plac ­
inga timing mark on the flywheel 180
0
from the TC mark. Then re­
peat steps 1 - 5 substituting cylinder 2
101-
cylinder 1 and the new
timing mark for TC. Later flywheels have BC (Bottom Center) mark.
B. Timing, Engine Running
1. Install an automotive timing light On the spark plug for cylinder #1;
following the manufacturer's instructions.