Originally Posted by Luddite
The purpose of a ballast resistor is to drop the voltage going to the coil once the engine is running. The design being that the coil`s operating voltage is perhaps as low as 6volts, thus the resistor drops the normal running voltage of the cars electrical system to circa 6 volts... However when the ign key is in the start position the ballast resistor is bypassed and the ign coil then receives whatever battery voltage is available to give it the best chance of generating a good spark.

Some such systems make use of a resistive length of wire to drop the voltage, so not always easy to spot and if in fitting a replacement coil a 12 volt coil is used, then in normal running it will be trying to operate in an under voltage situation..

The short answer is NO... (-:

Apologies if you already know all of that.

Again, happy to be corrected if I have made any mistakes..

Principles are fine but I think 9 volts more usual than 6.

Doug
2011 Plus 4 in Rich Maroon

1972 750 “ComDom” sprinter
1958 Triton 650
1992 Triumph Trophy 900