GM alternator, internal regulator or not?

Blackstack · Dec 4, 2010

This was supposed to be off a '74 Chev truck which to my understanding is an internal regulator vehicle. It doesn't look like anything I've dealt with in the past as far as being an internal regulator alternator. Can anyone identify it?

redtom · Dec 4, 2010

Not internally regualated. Internal ones have the spades the flat way.

ASEguy · Dec 4, 2010

Redtom is right. Older GM internal regulator alternators had a "D" slot in the back where you could full field the alternator and determine output. Gerard

Bob · Dec 4, 2010

It's a "10DN" series EXTERNALLY-REGULATED Delco.

Jon Hagen · Dec 4, 2010

Yep, an old external regulated Delco 10DN.

If the plug is on the rear, and terminals arranged like this {II}, the alternator is externally regulated.

If the plug is on the side of the alternator and the plug terminals are arranged like this { - - }, then it is an internally regulated SI series Delco alternator.

Billks · Dec 4, 2010

the terminal labeled grd is the wire that ground the alt to the regualtor. this alt requires 4 wires and not 3.

old · Dec 4, 2010

Terminal pharrel (sp) to the shaft is external reg. Terminals point up/ out away from the shaft internal reg.
Wasn't tell a bit later that the internal reg type came out. But if you go by what I have said and it is Delco you can spot the internal reg. type a mile away

Jon Hagen · Dec 4, 2010

One thing that can foul up your day when picking junkyard Delco alternators is a goofy crossbred unit built by Delco in the mid 70's
Production of the 10DN alternators had stopped, but for some reason GM still put the external regulators on small cars like the Nova.
The alternators on those cars used the same design as the internal regulator SI series, but did not have an internal regulator or diode trio.
They had a goofy brush holder and stator connection that accepted the old square,parallel terminal regulator plug. The Rear alt case had an odd shaped plug hole (kind of like a Chevy bowtie emblem) that would accept either the old square 10DN plug or the long SI plug.

These qdd ball alternators could be converted to an internal SI type by just removing the original setup and replacing it with a stock SI type brush holder, diode trio and internal regulator.

Always pays to look at the regulator plug hole when picking a junkyard Delco SI off the pile.

John M · Dec 5, 2010

Id have to see if I could find the numbers now, but i have this alternator on one of Ms. There is a small box that plugfs into the place where the blue and white wire are, and has a wire goingto each of the two post. (Then the wire goes to the gauge to show the amp output. The guy who set this up for Dad years ago has now passed away, and I dont know the details, I just know it works great, and has been for 15 or more years now. There is also another configuration Dad used on another M, where one of the spaded wires went to a Dodge type cutout, and then to the coil. It worked fine as well.

teddy52food · Dec 5, 2010

I have a regulator for it if you need one.

Owen Aaland · Dec 6, 2010

(quoted from post at 20:27:31 12/04/10) the terminal labeled grd is the wire that ground the alt to the regualtor. this alt requires 4 wires and not 3.

Actually this alternator can work properly with only two wires. The large output terminal must be connected to battery voltage. The case is grounded and does the same electrically as the ground terminal. The F terminal is connected to one brush and needs to have voltage applied to it from the voltage regulator to control charging rate. The other brush is grounded internally. The other terminal at the plug provides voltage out as means of controlling a light and commonly used to control a relay in the voltage regulator but is not necessary for the alternator to work.

GM alternator, internal regulator or not?

Blackstack

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redtom

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ASEguy

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Bob

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Jon Hagen

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Billks

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old

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Jon Hagen

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John M

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teddy52food

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Owen Aaland

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