67Dart273 said

You guys are dancing around the answer in a backwards sort of way. ALL US, anyways, manufacturers used a ballast type setup. GM and maybe Ford typically used an "in harness" wire resistor, as opposed to the Chrysler ceramic resistor

THEY COULD HAVE designed a 12V coil that would operate directly off 12 (actually 14) and been done with it.

THE REASON 12V cars were designed in this manner is SO THAT you can have a hot spark for starting!!! The ballast is bypassed during start, so that you normally get pretty much the same hot spark during cranking as you do during running.

Ford and GM both do this by an extra set of contacts in the starter solenoid, Mopar did it with an extra set of contacts in the ignition switch, the infamous "brown" "ign2" circuit.

So I'll say it once more. THEY COULD HAVE just designed a coil to operate directly off the battery. Some tractors (12V) do this very thing.

On an aside, ballasts are NOT exclusive to 12V vehicles. We once had a 6V Ford flathead 6 in what had been a grader, and my Dad built a homemade tractor out of it. I still remember the little ballast hooked right on the 6V coil, with a little ventilated tin cover. This would have been a late 40's or 50's engine.

Here's one listed as OEM for '30's Fords. The resistor itself on this part looks exactly as I remember it all those years ago

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