What does a ballast resister do?if it is missing could this be why my points melt the plastic parts off.Can anyone describe a basic wiring diagram for points type setup starting from battery. Thanks bentspoke

Fairly simple system actually. The resistor, or resistor wire, is connected in series with the main power to the coil. With the ignition switch "on" the voltage is reduced to the coil and points. You have to use a coil that is designed to "use external resistor" only. (usually says this on the coil.) A separate wire from the starter gives the coil full voltage only for starting. This terminal is the outer (away from the block) small one on the starter. One other note here; Make sure you don't leave the switch on with the engine not running and check to see the coil is not getting power on the "acc" spot on the switch. This will really heat up stuff around the ignition system, can burn up the wiring sometimes.

[This message has been edited by tom3 (edited 09-18-2000).]

A ballast resistor lowers line voltage from the battery level to a level that the points can live with. Most times, we see between a two and three volt drop with a resistor or resistor wire.

There are two different types of ballast resistors, a ceramic type that is mounted to firewall or fenderwell, and another that is literally a set length of resistor wire, the length giving the proper resistance. These resistor wires are run through the loom, just like any other wire, and are sometimes hard to identify.

Chevrolet uses a wire that has a silver atranding, black vynil insulation, and another vynil outer cover, white, but usually discolored and has a woven cloth type appearance.

You are safe to assume the lack of a ballast resistor can and will cause the point damage you have seen, along with a defective coil as well.

Thanks to both of you,I think we have a missing resister wire.Much appreciated. Bentspoke

Easy enough to check. Connect voltmeter to the positive terminal of the ignition coil, Turn key to run position, engine off, read voltage. Start engine, read voltage again. There should be a lowering of voltage after the engine starts, from a higher voltage with just the key on and no engine run.

Same voltage, start, key on-engine off, engine running, no resistor in place.

Please post results, and we'll see what you have. There is an easy way to add a resistor to a point system, and IF you need it, use a NAPA ICR13 (porcelain, bolts to firewall or other easily accessed spot) ONLY IF YOU FIND YOU NEED ONE.