Boomer880

I have a mystery wire on my 1970 454 with an AT. Given it is shielded (white), I think it is the resistor wire, which should go to the + side of the coil. I have two pictures of the current wire on the + side of the coil. It appears to be shielded as well and yellow-ish in color. In the current condition, the car starts and runs fine. I just picked up the car, so I have not driven it more that 5 miles (all went well). The current wire does not have a capacitor on it, so it does not seem to be a the radio capacitor wire. I saw one post with both wired together on one connector at the + terminal. Should I have both wires to the + side??? Or, is this mystery wire something else? Newbie to wiring, and I don't want to fry anything if at all possible. Thanks.

7T1vette

I suspect that you are correct. If you check the starter solenoid, I would bet there is only ONE ignition wire location on it. The stock starter solenoid had TWO ignition wires: one labeled "S" for 'start' and one labeled "R" for run. Both were routed to the power side of the coil. The 'S' wire had 12vdc on it; the 'R' wire was a resistor wire which limited current to the points and coil so that they wouldn't overheat/burn.
If your car has been converted to an electronic ignition system, it may only need the 12vdc power feed. If it still has the stock points system, you would do better to have the stock-type starter solenoid and BOTH ignition wires run as intended.

lars

Close, but not completely correct...
The "+" side of the coil, on a standard points-type system, has 2 wires on it. The one wire is a cloth-wrapped wire which is a resistor wire coming from the ignition switch. This wire is "hot" any time the ignition is "on," and it provides a voltage drop to the coil and points when the engine is running through the cloth-wrapped resistor wire coming from the firewall fuseblock terminal. The second wire on the "+" side is usually yellow, and it goes down to the "R" terminal on the starter solenoid. The "S" side of the solenoid usually has a purple wire on it, and this wire is hooked up to the ignition switch "start" position. When the "S" wire goes hot with voltage supplied from the ignition switch in the "start" position, the solenoid is energized, and the starter engages. At the same time, while the solenoid is activated, power is applied to the "R" by the energized solenoid, and this provides a full 12 volts to the coil and ignition system for better cold-starting. As soon as the starter is disengaged, the 12 volts at the "R" terminal is terminated and the coil primary side is fed from the reduced-voltage wire coming from the ignition switch through the firewall fusebox connector.
The radio interference suppression capacitor also attaches to the "+" side of the coil.

Lars

7T1vette

Thanks for the 'adjustment', Lars. Sometimes, the old noggin' doesn't remember all the details correctly....

lars

It's all good, Charlie! You always provide good, positive comments that people appreciate.

Lars