Ballast resistor

[bobs66440]

I know it's not a Mopar but I know most Mopars run them so...my Father has a '54 Chevy that we converted to 12 volt and we were told to run a ballast resistor with stock the Chevy alternator, coil & distributor. We just replaced the coil that went bad and I assumed the ballast resistor was to blame. We've tried 2 ballast resistors so far and in both cases the volt reading is high at the coil (10-11V) at the coil compared to what I was told it should be (7-8V). Is my assumption correct?

[Just 6T9 CHGR]

What is the ohm reading of the ballast across the terminals?   A lower resistance value will give you more voltage at the (+) side of the coil....

[bobs66440]

I took an ohm reading and it's between 1.3-1.4 ohms and it's a points ignition. The one on my Charger reads 1.6 ohms

[Just 6T9 CHGR]

Well thats odd then...when are you checking the voltage reading?  Engine running or just key on, engine off?
A stock coil will require a ballast of 1.1-1.3 ohms so not to overheat....this generally nets you about 6-7v at the coil.
Lower resistance ballasts (for ex the MSD .8 ohm one) will net you 7-8v at the coil

[bobs66440]

I think I just realized that the reading should be taken with just the ignition on and car not running...? I did it with the car running...

[Just 6T9 CHGR]

I think I just realized that the reading should be taken with just the ignition on and car not running...? I did it with the car running...

[bobs66440]

I think I just realized that the reading should be taken with just the ignition on and car not running...? I did it with the car running...

Thanks for setting me straight!!