Resistor

[TCPDRETIRED218]

Am switching a 1953 Ford NAA Jubilee over from 6 to 12 volts.thought i heard you don't need a resistor if your using a 12 volt coil
Is there any truth to that rumor??

 

[Jim.ME]

You do not need a ballast resistor if you use a coil designed and wound for 12 volts, with no external resistor required. Standard Motor Products # UC 15 and NAPA Echlin # IC 14 are a couple of those.

 

[TCPDRETIRED218]

As I thought thanks!!

 

[Hemmjo]

Depends on the 12v coil you get. Some 12v coils are are designed to be used with a resistor. These are wired so the resistor is bypassed when the starter is activated. Full voltage then flows to the coil when starting. After starting, the current flows through the ballast resistor.

Just be sure you get a 12v coil that does not require a ballast resistor, like the ones Jim listed above.

 

[olddavid]

If you already have a 12 volt coil that does require a ballast resistor they are available for older model cars with point ignition. Chrysler had an external one but I'm not sure the ones for electronic ignition will work. I changed a Chrysler 5th Avenue over to point ignition and it seems like I tried it but ended up getting one for like a '68 model. I'm not sure what Ford used. I believe GMs were resistance wire going to the ignition but bypassed by engaging the starter solenoid. The run voltage should be about half the battery voltage but full voltage when starting.