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#97466 10/04/2006 12:20 AM | Joined: Dec 2004 Posts: 1,897 Shop Shark | | Shop Shark Joined: Dec 2004 Posts: 1,897 | 1940 gmc positive ground 6 volt currently.
When I rewire this using a wiring harness from the venders wil it still be positive ground? How does that work with an alternater. I have a positive ground heater that I would like to use. I guess I could rewire the heater for negative ground.
Any thoughts? | | |
#97467 10/04/2006 2:05 AM | Joined: May 2001 Posts: 7,438 Extreme Gabster | | Extreme Gabster Joined: May 2001 Posts: 7,438 | If you use the alternator you will have to switch to negative ground. The heater motor will have to be replaced or it will run fast and backward. No that won't make it cool.  | | |
#97468 10/04/2006 4:01 AM | Joined: Jul 2004 Posts: 5,708 'Bolter | | 'Bolter Joined: Jul 2004 Posts: 5,708 | bigbadswingdaddy,
This is my second attempt at a reply...the first made no sense..I hope this one is better.
If you are going to be installing a alternator, then this isn't going to be a restoration...correct!
The wiring harness will still have its wires going to the same physical location, positive or negative ground.
You will make the determination yourself when you connect the 'few' wires that would be polarity sensitive, which way you want to go.
If you are not restoring, a negative ground system would be much easier to deal with.
Your heater fan motor very well might work on negative ground, it depends on how the motor is constructed internally. It would be prudent to install a voltage reducer before a 6 volt fan motor to prolong its life.
If your fan motor will not rotate in the proper direction when polarity is switched, maybe a new 12 volt, negative ground motor would be a thought.
Alternators are available in 6 volt positive ground so they could be available in 12 volt positive ground as well. The burning question would be why stay with the positive ground if not a full blown restoration.
Stuart | | |
#97469 10/04/2006 4:18 AM | Joined: Dec 2004 Posts: 1,897 Shop Shark | | Shop Shark Joined: Dec 2004 Posts: 1,897 | I kinda like those GMC factory quirks. Since the harness I bought is for a chevy, the negative ground seems easier to install. I'll have to see if I can find some wiring diagrams to help me through the process. The instructions are vague at best.
I tested that motor with both 6 and 12 volt sources. It seemed to like the 12 volt... not to fast, not to slow. Pushes a little more air at 12 volts. It would probably work pretty well with a selector switch. This heater motor is going to be hard to replace cause the shaft is long on both sides. It has a squirel cage on one side, and a 4 blade propeller on the other.
Anyway, I'll see what I can come up with. I have a 100 amp chrome alternater I was planning to use.
Cletus and Atomarc thanks for the replies | | |
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