Look, the entire reason that the "big three" car makers originally started to use ballasts was so that you could have a HOTTER SPARK during CRANKING.
This was especially important at about that time, because "at around" the time that 12V came along, engines also started going up in compression ratio, and so a better starting spark was a LOT more important than on, say, our old Farmall Regular (This is not our old one, but she can handle my Farmall any time)
So why, how, when, and does, this work?
Ford, GM, Ma, and even Kaiser/ Nash / Rambler / AMC used the same scheme on 12V cars.
With the engine running, the charging system at about 14, and cruisin' down the road, the coil / resistor combo resulted in "somewhere around 10-12V AT THE COIL.
But STARTING, and especially on that cold *** winter night when Mom just had to get to the hospital in time,
(Ok maybe she's NOT pregnant but I didn't spend a lot of search time)
the battery is cold, the starter dragging, the battery voltage goes LOW.
So if you did not bypass the coil resistor, there would be VERY low voltage at the coil, who knows, with the poor battery gagging along at 9?? volts at the starter, the coil might only see 4 volts!!!!!!
HEY NO STARTEM UPEM!!!!!
So in the case of Mopar, in the ignition switch, and in the case of "the rest," in the starter solenoid, the resistor gets BYPASSED during crank, and so now you have AT LEAST 9V at the coil, even on that horrid winter night. And on a nice summer night, you might get more like 11V (read above) which is closer to the voltage at which the coil normally sees when running.
Think about that. That is all. Six two and even, over and out
