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SHADE DOCK MECHANIC
by Steve Merjanian
Thorny Ignition Problems
Recent problems with a friends
ignition system caused concern and consternation. The points
in a typical distributor switch the negative side of the
ignition coil’s primary winding in synchronization with
engine RPM. This current has to be carried through the
distributor body without shorting. As these components age,
the phenolic insulation material, around the current carrying
stud, breaks down and shorts out to the distributor body. If
this stud is bent and the insulation cracked, it has to be
repaired or replaced.
A one inch long, number 8 machine screw with a hexagonal head
is the best choice, however a slot head can also be used. Get
some heat shrink tubing of appropriate size and cut it to
about 1/2 inch in length. Slip it over the machine screw, butt
it up to the underside of the head and shrink it in place with
the heat from a match or lighter. Use vinyl washers on the
outside of the distributor body and also on the inside flush
up to the vertical post where the point and the condenser are
connected. Metal washers should be used external to the vinyl
washers to provide a good contact area for inside mounted
point/condenser and the outside mounted primary coil negative
wire. Use a continuity checker to assure there are no shorts
between the body of the distributor and the end of the machine
screw stud when the points are open. If the balance of the
ignition components are in good shape, you should see a small
electric arc accross the point gap when the engine is cranked
over.
The second problem occured when the engine suddenly stopped
working and once again we had no spark. Typically a coil will
fail slowly as indicated by a redish spark instead of the
desired white spark. To see the spark, remove the ignition
wire from the center of the distributor cap and place the end
about 1/8 of an inch from the engine block. Then crank the
engine and ascertain the brightness and color of the electric
arc. When we get a sudden engine failure, the condenser is
suspect and has to be replaced. I have witnessed condensers
working perfectly in the fall and failing during the spring
fitting out. I believe freezing winter weather reeks havoc
with the dielectric insulation on the inside of a condenser.
For the record, a condensor (automotive term) is really a
capacitor (electronic term) which limits the current at your
points to reduce erosion and also provides the the ringing
voltage for the coil’s primary winding. Instead of filing
your points, use contact cleaner and then burnish away the
oxidation by rubbing some cardboard between them. I hope these
few hints prove helpful.
Happy Antique Boating!!!!!
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