by Steve Merjanian
Recent problems with a friends ignition system caused concern and consternation. The points in a typical distributor switch the negative side of the ignition coils 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 coils 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!!!!!