Alternator wiring

Last night at a cruise-in I saw a '67 Coronet that had unusual wiring for the alternator. It had 2 field wires, but one was powered directly from the alternator output terminal. I told the guy that I had never seen that before, and asked him why he had done it? He said that it had been that way for years, and he couldn't remember why, but thought that he had done it when he installed his MSD ignition. I didn't see a voltage regulator on the firewall, and I asked the owner if powering the field that way made the alternator charge full out all the time? He said he didn't know, but the thing puts out just about 15 volts whenever he checks it. Has anyone seen this done, and will it cause the alternator to be on full output all the time?

It used to be quite normal to buy a rebuilt or new alternator for your pre '70 Mopar and it have two field connections for the later cars. In the box was a jumper for the extra field connection to the output terminal.

Shorting the other field connection to ground will cause full output.

As far as not having a regulator??? Who knows on that one...

Thanks for the info Big John. Possibly he had the regulator mounted in an abnormal location.

If he was running without a regulator and the alt is pumping 15+ volts he would boil the battery in a very short time.....not to mention possibly torch some wiring. If he hasn't, then he's just been really lucky to this point

sure the alt doesnt have a built in reg.

He said he's using a late model alternator, but I'm not sure. I told him that I was concerned about him running voltage that high, because of possible battery and wiring damage, but he said he's had no problems. I guess he must have a voltage regulator mounted where I wasn't able to see it.