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Cheap Pencil Coil Polarity Test:
Because Model A's & Model A repop parts offered today are rather unique, listening to the many experiences indicated in messages given by other Model A owners, (approximately 16 on this thread,) one can see many have reported Model A "coil" problems; e.g. message nos. 13, 23, 30, 31, 34, 37, 38, 42, 59, 64, 65, 68, 101, 109, 115 & 147.
Supposedly, with even a minor breakdown in current flow, coils can get hot & cause ignition problems if polarity is not correct. Marking on coils are useless if marked (+), or (Dist.) or (Bat.) or (Ign.) if the coil was intended for a negative ground battery & the coil is installed on a positive ground battery vehicle -- or vice versa.
Coils can operate if not wired correctly but can lose 15% - 20% efficiency
plus lower gas mileage, & in some cases get hot & cause missing when hot -- after coil cools down, engine runs fine again.
This may or not be the problem, but below is an inexpensive, simple polarity test you may want to try to verify your coil polarity:
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If you are still skeptical about all this, there is a quick way to check directly which way the current is flowing in the high tension circuit. Disconnect a spark wire from a spark plug (or the coil wire from the distributor cap). Hold this HT wire near a grounding point (or near the connector end of a spark plug), and position the tip of a graphite pencil in between. When you crank the engine (no need to start or run) you can observe the resulting spark jump between wire and pencil, and between pencil and ground (or spark plug). A flare (hard to see) toward the plug (or ground) shows correct polarity while a flare toward the coil shows reversed polarity. If the flare goes toward the coil, just switch the primary wires on the coil and make note of the connections for future reference.
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Can't hurt to reach for wood chips when drowning.