What's the purpose of the resistance wire?

The ballast resistor converts the ignition voltage to the full 12 volts when the engine is cranking. Once it starts the ignition system runs at 8 volts.

8 volts isnt enough to fire the engine, particularly when cold and if it were to run 12 volts all the time it would fry the points.

I've got electronic ignition. I'm re-wiring the car. I've left it as it was. That should be ok?

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Originally posted by Gdub


The ballast resistor converts the ignition voltage to the full 12 volts when the engine is cranking. Once it starts the ignition system runs at 8 volts.

8 volts isnt enough to fire the engine, particularly when cold and if it were to run 12 volts all the time it would fry the points.

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Not 100% correct.

While cranking your ignition coil has a reduced voltage (approx 8vdc) and hence the ballast resistor is bypassed during this process. As the ignition system is designed to operate effeciently at this lower voltage it needs to be regulated once the car starts. Once the engine is running the ballast resistor is back in circuit to maintain the lower initial coil voltage.