Ballast resistor education

[Steve D.]

63 SB. In the AIM it appears to show one wire from the harness connecting to one terminal of the resistor, and nothing connecting to the other terminal. Have I got that right, or did I miss something? This seems like a dead end instead of a series connection. Also, in my pre-disassembly photos I can see the one wire from the harness to the resistor, as shown in the AIM. Connected to the other resistor terminal is a wire that goes to the electric choke on the carburetor (NOM, Holley 4160) I assume that this was a convenient source for the choke, but I don't understand why. I am obviously electrically challenged, so any explanations would be appreciated.

Steve

[Stephen L.]

Re: Ballast resistor education

The ballast resistor reduces the voltage to the coil in "run" conditions. If the coil were subjected to 12.5vdc continuously the life expectancy of the coil would be drastically reduced. The voltage to the coil should be in the 7-8 vdc range.
The ballast resistor should have a pink #12 wire on one end coming from the ignition switch. The other end should also have a pink #12 wire running to the coil. Assuming the electric choke is hooked up to the 12 vdc end this point serves as a "switched" source of power for the choke.

You are probably missing the wire from the resistor to the coil as it could have been replaced with a wire NOT in the harness and was removed and forgotten when it was taken apart. I assume the engine is not running under this condition or the ignition system has been replaced by an aftermarket unit that does not utilize the ballast resistor and the wire was discarded.

If you have the stock ignition system then the wire is required as well as a wire from the starter solenoid "R" terminal to the positive side of the coil....this is also the point where the "missing" wire would terminate on the coil. This additional wire from the solenoid puts 12 vdc on the coil during the starting sequence of the engine to give a higher voltage spark for starting. Once the key is released to the "run" position this 12 vdc is disconnected via the solenoid contact and the ignition reverts back to the 7-8 vdc range

[Steve D.]

Re: Ballast resistor education

Steve

Thank you for the explanation. After I read your post, I found another photo angle that shows the "missing" wire. Behold, it is pink and runs to the coil!

Steve