During some starting situations, the load of the starter motor will drop the battery voltage to about 9.5 volts. Using a coil that needs 12V to fire well results in a weak spark during a cold start when you need a good one. By using a coil that works on 9 volts, and dropping the voltage from 12 to 9 during normal running, then bypassing the resistor during starting, you get a good spark all the time.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
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