Thread: need oldtimers know how

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Calling on the older crowd for help. I remember my Dad showing me how to detect polarity of coil/coils at points with a pencil. Do not remember all of it but if you have coil wired properly the spark at point contacts will jump from arm to fixed pad of is it visa versa.??
I have an old OFFY/ Drake brought into my shop and the polarity markings on the coils are not visable. It has a coil for each set of points and trying to use old parts so period correct. I did not have an old used coil with marked terminals kicking around to compare with and hate to buy 1 just to be sure. Coils and cond. are good as the color is bright blue so just need to wire polarity properly.
What is correct? spark jump from contact to pad or the other way around? Remember using a pencil and paper with corbon scrapped off the pencil to check direction of flow. but it is foggy??
The J Hunt magneto was often used but is not present on this baby.

I understand that if you hold a wooden pencil's lead point between plug wire and ground - with an air gap both sides - you'll get an indication as to proper coil polarity.

If the visible spark is on the plug wire side, polarity is reversed.

If the visible spark is on the ground side, polarity is correct.

A further indicator of correct polarity is if your spark plugs don't seem to last long - maybe 1500-2000 miles at most.
Assuming of course, the engine is in correct tune.

Correct polarity should have your plugs lasting the usual 10,000 miles between points ignition tune-ups.

C9,
Thanks for the info, I also got an email telling me an ohm meter will identify polarity by telling you primary from secondary side . one terminal to coil tower will show o ohms and other terminal to coil tower will show about 6 ohms. The 6 ohm terminal is the secondary side of coil. THANKS ALL. appreciated a bunch.. jeff c

If you also happen to have a scope handy , the ignition trace will be up side down if the polarity is reversed .

geo