Re: Coil Identification

Posted by Bob Bidonde on April 30, 1998 at 06:16:27

In Reply to: Coil Identification
posted by Tom on April 29, 1998 at 23:24:35

This is a bit of reasoning rather than science. Pre-computerized 12-volt ignition systems use a 6 - 8 volt coil and a dropping resistor. That is, these coils start on 12 volts, but once the ignition key goes into the run position, either a resistive wire or inline resistor dropped the the voltage at the coil to 8 volts. Thus, the 6-volt coil did not go away until computers took over the igition function sometime in the 1980s. The exception to this are Chrysler products and high energy systems used by GM & Ford, as some of these used 12-volt coils or had an internal resistor. So the probability that your coils are 6-volt is high.
I suggest you try the coils on a known good performing 6-volt ignition. If the spark produced is blue and strong, the coils will be suitable for 6-volt use. On the other hand, a 6-volt coil run on 12 volts will get excessively hot and fail prematurely.
Not all original Model A coils have a Ford script. The most recent issue of the Model A News and the judging standards will give you some idea of the various original coil markings.

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