Request for Knowledge: Generator to Alternator Conversion - 57 Pontiac
 

Good Evening,
My generator failed on my 1957 Pontiac Super Chief this evening so I'm planning to replace it with an alternator. Reading other posts it looks like a three wire setup might be the best route. I'm not sure I want to drop $400 on a Powermaster setup so I'm looking at standard ACDelco Alternators. Has anyone done this on their 57 Pontiac? I'm curious in the following:

- What alternator did you order? Any recommendations on what to ask for at the local parts store?
- Does the Charge Indicator remain functional with only one indicator light wire from the alternator? Or do I have to wire through the regulator box.

Any help and guidance is appreciated!

Link to simplify installing newer alternator into older generator equipped vehicle:

https://vintageautogarage.com/conten...gram-10.14.pdf

I put a Delco 10SI type alternator on the 347 Pontiac engine that came in my '57 GMC truck. It is a 3 wire. Got it from Either O'Reilly's or AutoZone, cant remember which. Generic number is 7127. Regulator is built in to the alternator. Here is simple wiring instructions: https://contentinfo.autozone.com/zne.../86/tt-598.pdf

I'd argue against using the diagram that Brad posted because it does away with the advantage that a 3 wire alternator has. By connecting the "sense" wire (#2 in my diagram & the one on the right in both diagrams) directly to the alternator's output connector you effectively turn the alternator into a one-wire model. It will sense and regulate the voltage to the output lug.

Instead, the #2 wire should be connected to a point that is electrically "far away" in the wiring harness. That way any loss in the electrical system would be "felt" back at the alternator's sense pin and the regulator would increase the voltage to make up for the loss.

Bill, I've been doing the connections on non GM uses just like the diagram shows since the 70s with no problems whatsoever. Running the wires further just to do the same function is useless IMO. Whether the circuit is contained within 6 inches of wiring, or 10 feet. That setup pictured has worked fine in every car, truck or piece of machinery I've ever wired, and that has been a bunch.

That wiring worked on my 455 Jeep with a Western electric over hydraulic plow being run for probably 20 years, the voltage sensing will work just fine. If the OP wants to make it more complicated by all means do the other way. I believe in simplicity, especially when it comes to wiring.

I agree that connecting the sense winding to the alternator's output will work and is the easiest way. It just emulates a 1 wire alternator.

If you wire it that way and then check voltages to ground electrically further away in the wiring harness you'll probably find that the voltage is 1/2 to 1 volt less than at the output of the alternator when heavier loads like A/C and headlights are on.

I'll be a contrarian :) and ask if you really need to replace it...often, all a generator needs is set of new brushes and bearings and a good cleanup to get it working again. It's a lot simpler and cheaper, and if your car doesn't have a lot of power robbing devices (big stereo, a/c, etc.) an alternator may not be necessary. After all, the car has lasted over 60 years without one.

I've done the conversion with a stock Delco Internal regulator alternator and also a 1 wire alternator I bought from a local shop for Way less money than the Big Brand ones. Either way works very well. I always have connected the "sense" wire to the positive post with no problems. I have done the conversion to internal regulator alternator many times.

alternator
 

I would go with the delco cs130 with the remote sense wire. I find that the remote sense wire will give you a higher voltage at the battery than the jumper setup. I also find that the REAL remanufactured Delco's are easily bought and more reliable. Billk

Someone makes an alternator that looks just like a generator but I can't remember who it is. I think it is a bolt in replacement.

alternator
 

I don't think I can afford this. It may be available for less. Billk

https://vintageautogarage.com/powerg...SABEgK3P_D_BwE

Here is a good link http://www.madelectrical.com/electri...elcoremy.shtml that gives examples of what to order at the local parts store. Go down a ways and look under application data. If you don't find the "clocking" that you like, don't worry about it. Just remove the 4 bolts and turn the back to where you like it.

As an electrical engineer, I recommend going the three wire route. If you already have an idiot light on the dash, it should be easy to wire that way. Getting the sense wire as close to the battery as possible will give you the best charge voltage. With the head lights on and other accessories it can make a couple of tenths of a volt difference in charge voltage. If you don't drive at night, don't have AC, a big stereo, or other electrical accessories, then the one wire will be OK. The other way to make the one wire OK is to use a fat and preferably short wire. Say #10 or larger. The factory did not run three wires because that extra wire that they needed to use up. They did it because that was the most cost effective to get the performance they wanted.

This is brilliant.

and to be totally contrary: I found the basic 10si alternator with 3 wire hook up will work just fine only using the threaded post. Wire it directly to the battery. When you fire up the car, bring rpms to approximately 2000 and the alternator will self excite. The catch is you'll need to wire in a volt meter to watch your voltage.
I've bought the kit to swap a one wire regulator, new brushes and bearings for less than 10 bucks in the past and done a bunch of them . Either way it works. I was given the newer, smaller GM alternator and made up brackets to attach it to my 370 Pontiac in my 34 ford. Iirc, I used only the big post on that alternator too. My volt gauge says it works just fine and has been for 4 years now.

Bill, what brackets did you use?

30 years ago I chopped up the stock '57 bracket by moving the rear tab towards the front. A friend (who welds) and I mounted the alternator on a piece of all-thread using nuts and washers to position the alternator fore and aft until we got it right, then moved only the rear tab (if I remember right) forward to meet up with the alternator.