Inliners International Forums General Discussion Engines internal or external resistor Coils?

I've tested many GM coils with a meter,some were stamped 6 volt on the casr,some were 12 volt.All of them measured 1.2-1.5 ohms between the primary terminals.That means all the coils I tested had the same primary resistance reguardless of listed voltage which also means the coil cares less about the system voltage so long the voltage it sees is around 7.5 -9 volts for proper points life.Putting a voltmeter on a running 12 volt system after the ballast resistor but before the coil, shows about 9 volts on GM vehicles.
12 volt points ignition systems uses a total of 3.0 ohms or so,half of that figure comes from the ballast resistor.Bypassing the resistor on starting is benificial on many engines,but not all.