Check the insulation on the high-tension
spark plug lead. If it is cracked or deteriorated
it will allow the spark to short to ground when
the engine is revved. This is easily seen at night.
If arcing occurs, hold the affected area of the
wire away from the metal t o which it is arcing,
using an insulated screwdriver (Figure ll), and
see if the misfiring ceases. If it does, replace the
high-tension lead. Also check the connection of
the spark plug cap to the lead. If it is poor, the
spark will break down at this point when the
engine speed is increased.
The spark plug could also be poor. Test the
system with a new plug.
Incorrect point gap or a weak contact
breaker spring can cause misfiring. Check the
gap and the alignment of the points. Push the
moveable arm back and check for spring ten-
sion (Figure 12). It should feel stiff.
On models with electronic ignition, have the
electronic module tested by a dealer or sub-
stitute a known good unit for a suspected one.
If misfiring occurs only at a certain point in
engine speed, the problem may very likely be
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