Electrical: Alternator 3 wire hookup

[Warren Webb]

I got a smoking deal on a 3 wire alternator from rock Auto to install in my 62 Champ. Now, I'm fairly literate in things mechanical but all the wiring diagrams I've seen aren't clear to me. The alternator is a 3 wire spec'd for a 85 GMC pickup & yes, I got the short harness along with it. What I don't see is if I need an external voltage regulator with it? Do I use the existing 10 gage red wire for the main connection? Where do the other 2 wires from the short harness go? I would like to keep the stock idiot light on the dash.

[StudeRich]

I think the GM Delcotron OEM 3 wire Alt. conversion is SOMEWHERE on Bob Johnstone's Site Warren.

http://www.studebaker-info.org/

[GrumpyOne]

I'm not sure if that particular alternator is the "famous" single wire alternator with internal regulator but if it is, the only wire needed to be connected directly to the (+) side of the ammeter is the terminal marked, "BAT" along with a small jumper available at most FLAPS to connect the two remaining terminals together. This simply allows the alternator to turn itself on but such can vary widely as I had one example in my '64 Champ p/u that needed a couple of minutes at higher-than-idle rpms to activate but it never failed.

[Kurt]

The 10 guage wire goes to the main output lug. The number1 connection goes to dash light. On my 61 Champ that is the white/black wire. The number 2 lug goes to the main output lug. (Make a pigtail wire). Make sure your charge light indicator has a good bulb in it. (Light comes on when key is in first position) if the bulb is bad the system won’t work correctly. I have done this conversion at least 3 times. If you have any other questions just PM me.

[Dan White]

Do a search on the forum. This area has been covered many times.

[StudeRich]

Most Forum Posts are about the Generic, everyone has one, POC, Single Wire Delco, NOT the OEM GM Type 3 Wire, which I THINK is externally Regulated.

[Kurt]

Here Is a diagram of how to hook up 3 wire alternator. They are internally regulated.

[Lynn]

There are two different 3 wire alternators. If the two prong plug goes straight in the BACK of the alternator, it needs an external regulator. Most likely, it plugs in from the side (right at the very back) like the illustration above. It is internally regulated. It uses the dash light as an excitor wire to engergize the regulator on start up. Without it, it will still charge, but not until you rev the engine over 3000 rpm or so.

[sweetolbob]

Kurt's got it correct. That's the way I've wired that era alternators for a long time. They start getting difficult when the 90's GM alternators show up as they have 3-4 wires in the harness as well as the power lead to the battery. There are a number of combinations with these. Don't ask me how I know as I fought a 92 serpentine alternator in my 74 Avanti for a couple of hours. AS a bonus, they won't charge without the exciter wire no matter the rpm.

Be sure you have the indicator wired as in the diagram. If it's to small just google GM 1985 alternator wiring and you'll find what you need.

Bob

[bensherb]

If it looks like this:It wires up like this:

[RadioRoy]

What type of alternator would one use if they wanted to retain the ammeter? Or if it is the same alternator, how would it be wired to retain the ammeter?

[oilnsteel]

I think Randy Rundle at Fifth Ave Automotive has a gizzy to do that.

JT

[bensherb]

What type of alternator would one use if they wanted to retain the ammeter? Or if it is the same alternator, how would it be wired to retain the ammeter?

Same way, just stash the light bulb out of sight or, if I remember correctly, replace the lamp with a 10 ohm 5 watt resisitor or 1N5408 diode. Or keep the light where you can see it, if nothing else it will tell you immediately when you throw a belt.

The ammeter just goes in between the ignition switch and all switched load as it would otherwise.

[BrianInReno]

Need to replace the dead generator in my '58 Silver Hawk. Looking at a new one-wire GM 10si or 12si style alternator. Questions:
1. Will the alternator line up correctly with the fan belt when mounted on the stock adjustment arm bracket?
2. These alternators have internal regulators. If the + wire is retained from the battery to the voltage regulator can the stock voltage regulator be retained as a terminal block for the Ammeter?
3. Any sources for a mounting bracket to the stock bracket (for the original generator) on the engine block/intake manifold?
4. What wire gauge would you recommend from the alternator to the + battery terminal? Is 10 gauge adequate?
Thanks fpr the help.

[Warren Webb]

Based on a spare generator/ bracket & cylinder head the alternator pulley lines right up. I ordered a 3/8" x 8" long bolt from Bolt Depot for mounting. That will require drilling out the bracket to accept the 3/8" diameter bolt.