VCCA Home Forums TECHNICAL - GENERAL Electrical - 6 volt Mystery wiring

Today’s problems I think are related.
1. The engine seems to be running fine except the rpm’s are set at 850rpms and on it own it races to 1500 rpm’s without touching the car.
2. Without the ignition on, I turn on the headlights they start to flash. The amp meter clicks back and forth from center to discharge.
3. I was leaning on the fender and adjusting the carb and touched the bare shaft of the screw driver and the horn honked.

I’ve got a 6volt headlight switch ordered.
If I order a new wiring harness, will a 12volt kit work if I plan on converting to 12 volt someday.
Thanks

12 volt wiring will not work well as long as you're on 6 volts. Just get a 6v harness. The beefier wires will swallow anything 12v will throw at it. Unless you're running some kind of electronic ignition I don't see how an electrical problem will affect the idle speed. Others will be along soon with better ideas than mine. Electrical gremlins make my head hurt.

I did install a Pertronix ignition 1 month ago and installed new plug wires today. I also found with the positive cable of the battery disconnected I was using a continuity tester and found it sounded when I connected the ground and touched a positive wire.

Whatever you do always disconnect both terminals on the battery when you are not around the car.

My best guess right now is that you have some unexpected grounding of the wiring in the car. It is possibly at multiple locations.

You have not described the condition of the wiring in the car. If the insulation is hard or brittle it will crack and expose bare wires.

The electrical anomalies you are describing are often caused by improper or incorrect grounding. My guess is that those anomalies have damaged the Pertronix.

I am also interested in why you have the idle set so high. And how do you know it surges to 1500 rpm? If you added a tachometer it might not be compatible with the Pertronix.

The best I can tell is the wiring is old so it probably is a short to ground. I set the rpm’s using a portable tach. 800 rpm’s seemed to be the lowest I could go without it stalling.
What’s your thoughts on 12 volt wiring or 6 volt wiring?

As Tiny noted you need the heavier gauge wires if you are going to run 6 volts even for a while. You run the risk of overheating wires and creating a fire if you use a harness designed for 12 volts in a 6 volt system.

I think there is something else going on with your engine if the slowest idle you can get is 800 rpm. These Stovebolt 6’s will normally idle at as low as 450. I typically set mine at between 550 and 600.

So I understand I need to use the 6v harness because it uses a heavier gauge wire. Can I then use the 6v harness on a 12v system?
I also need to get an official 6v tachometer.
Thanks for your help!

Thanks Tiny

I didn’t realize that car wiring is the reverse of electrical wiring. 120v smaller wire, 240v larger wire.

Not so.

It's all about amperage.

Home wiring for 240v is usually larger only because it's used for appliances that draw a ton of amps... like dryers and stoves.

Thanks guys! Learn something new everyday. And today I learned it’s better to ask questions, than assume I know something!

That quote about electrical wiring is in correct. The size is always determined by the current,

These sixes will idle down really low. I would guess that you may have a vacuum leak.

Check all of your wiring. Anything that is old and brittle needs to be replaced. When we received our 41 much of the wiring was original. There where areas where the cloth insulation had disintegrated or been eaten. One short from a fire. We ended up replacing all of the wiring. Also doing the grounds.

Many 6 volt issues can be traced back to bad grounds. 6v systems seem to be more sensitives to bad grounds. Unless you are adding more electronics to your car the 6v system should be more than adequate. It may crank slower but that does not meant that it will start slower.

As far as the wiring size keep this formula in mind: Volts X Amps = Watts. If you headlight outputs 50 Watts with a 6v system it will require 8 amps. In a 12v system that same headlight will draw 4 amps. For this reason a 6v system will need larger wires to carry the current to the light.

If you replace you wires be caution off many on-line sellers. Get full copper, not copper clad wiring for your car. I would avoid the one harness fits all kits.

The horn honking bit tells me that you have something going to ground that should not be. Was the idle correct when the car ran on points?