How Do Points Work?-- No Spark!
I am going to
tell you only what you need to know to check your system,
not explain the whole theory of the system. There are a few parts
to the system. 1. points, 2. condenser, 3. charge
coil, 4. ignition coil, 5. flywheel magnets, 6. cam
|The points are a switch that
when opened cause the ignition
coil to fire the spark plug. This only happens if the "points",
smooth contact pads that touch together, are clean as to make a
connection when closed. There is a cam, that turns with the engine,
opens the points just before the piston gets to top dead center. When
points crack open, the spark plug will fire. The ignition coil gets
from the " charge " coil. mounted under the flywheel. As the engine
over, the flywheel magnet produces electricity with the charge
One end of the charge coil must be grounded. Some are grounded through
a tail lamp bulb, if bulb burns out there is no spark. Most are
directly to the stator "point" plate. From the other end of the charge
coil, power goes to the ignition coil, points, and condenser.
The condenser must be grounded. The other end of
the ignition coil must be grounded. The spark plug lead
off the ignition coil and goes to the spark plug, the spark plug also
have battery ignition, then when the ignition switch is on you have
to the points even though the engine is not turning over. You can open
the points with a screwdriver, they will spark the spark plug every
you open them.
**TIMING**: On the flywheel and crankcase there will be a set
of marks for timing.
Most times it will be a F mark for fire, and a T mark for top dead
When turning the engine, the points should just crack open as the F
lines up with the mark in the case.
When checking for no
spark, bear in mind that most times it is caused by
dirt or corrosion on the contact surface of the ignition
Ignition coils rarely fail, and if a condenser is bad you will get a
built up on one of the point contacts and a pit on the other.
check that the pivot for the points is not sticking, so they do not
be a small amount of grease on the cam lobe that opens the points to
the rubbing block from being worn down Most points will work set
at about 16 to 18 thousandths.
If you are trying to clean
points, use a very fine sandpaper and clean well after to get all
the dirt and grit out. Any piece of paper or lint caught between will
a no spark.
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Street | Madison,
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