ballast resistor?
Racer
Joined: Oct 2001
Posts: 271
Likes: 0
From: St Louis MO
Re: ballast resistor? (jonvolk)
It depends. Your car might have a resistor wire in it fron the ignition. Measure the voltage at the coil with the key on. If it's around 12V, you'll need a ballast resistor. If it's around 6, then you're OK.
Gary
Gary
Tech Contributor
Joined: Aug 1999
Posts: 14,380
Likes: 6,391
From: At my Bar drinking and wrenching in Lafayette Colorado
Re: ballast resistor? (Garys '68)
Your '69 should have the resistance built into a resistor wire feeding the coil as Gary states. To test, either make sure the points are closed or run a wire from the coil "-" side to ground. Then turn the key to the "on" position and test the voltage on the "+" side of the coil. Voltage should read between 6-8 volts. If you're reading battery voltage (about 12), you need to install a ballast resistor as Dave states or splice a new resistor wire into the circuit. Note that if the points are 'open" or if you do not ground the "-" side of the coil, voltage will read battery voltage even if you have a resistor wire in place due to no current flow.
Running points continuously in battery voltage will fry the points.
Running points continuously in battery voltage will fry the points.
Intermediate
Joined: Dec 2001
Posts: 47
Likes: 0
From: St. Andrews Manitoba
Re: ballast resistor? (jonvolk)
the resistor wire you need to look for is a "cloth covered " wire, typically dirty yellow in color. If you don't have one, go to a boneyard and find an old GM car from about 1962 up, and cut out the full length cloth covered wire and splice it to your existing feed wire. I did this on a 65 chevelle recently, and it worked fine. The resistor wire has stiffer than copper silver strands, which end up not passing 12 volts, but something around 8 to my understanding.
