Hey guys, I bought an 85 mustang distributor, an "accel" coil, stock 85 mustang ignition module, stock starter solenoid....but I need a ballast resistor. Which ballast resistor do you guys recommend? All I seem to find are aftermarket resisters and don't know which to choose. I converted this engine from EFI to carb and everyone recommended to go the duraspark II route.

 

We get into this a lot on the flathead Ford tractors when converting to 12v .

Each type of coil needs a certain numbers of ohms resistance in ratio to the voltage . The coil resistance has nothing to do with the rest of the ignition system . A 6v coil will work in a 12v system if you have enough ohms resistance . Too much and you have a weak spark , too little and you fry the coil eventually .

Best bet would be to go to "Accel's" web site and use the recommendations for their coil .

One neat thing about the resistors is when you first power the coil it is getting the full voltage and a hotter spark to start the motor . Shortly after the resistor starts working and drops the power to the coil , keeping it from overheating .

 

Stock resistor for 76-82 DSll is 1.1 ohms. For 85 I believe the TFI coil was used, and out of my knowledge base. As Ken posted, refer to manufacturer for whats recommended for which coil.