1970 Alternator Conversion to One Wire

[Dynamo Dan]

Project 2 this week on the 70 Monte I'm working on is putting in the new one wire alternator I am picking up. The oem Alt does not have enough output to run the Holley Sniper, Fans, Fuel Pump, Vacuum Pump, Stereo etc. Believe the one was less than 40 amps according to the shop. As soon as the fans kick on voltage dropped on the battery from 14.1v to 12.3v. So I took the original one to a good shop in Everett, Washington and they looked at it and went no way, not worth pumping up.  OGPI Special Delco name on the outside and total junk inside. I had 2 Voltage regulators they were the same, both Declo Branded, one buzzed very loudly, the other just wouldn't charge.   Open both up and it's just garbage inside of bent and misaligned contacts and poor soldering. 

 

Anyway we ordered a One Wire internally Regulated Alt from them for less than fixing this one would cost. I've looked around a bit I just need to be pointed in the right direction how to bypass the regulator. I know I'll still use the 2 wire plug on top of the Power output. But don't want to stack 2 regulators together. I was reading I cut and splice at the regulator? 

 

Thanks 

[jft69z]

What size output is your new alternator going to be?

[Dynamo Dan]

Supposed to be around 100 amps. Will be up sizing the output wire to 6-8 Awg to compensate. 

[jft69z]

Perfect, that's what I was hoping you were going to say 🙂

[Dynamo Dan]

Yeah 100 amps thru that old 12 gauge wire would not be a fun sight to see. Don't know if I'll go to the battery post on the starter as it's closer to run to where the existing one is on the terminal behind the battery. Probably just rebuild the alternator harness totally as I technically don't need the trigger wire but the light would be nice so I'll rewire it with the 3 and figure out what to do where the regulator is. 

 

[jft69z]

I put a 1-wire Powermaster alt. on my latest car, but I also used a new harness from American Auto Wire at the same time. They have their harness setup for a 1-wire alt., so bypassing the old external regulator wasn't something I had to deal with. 

There's plenty of info out there for bypassing the regulator if you're using a later, internally regulated GM alternator. A 1-wire conversion is even easier. Here's an article that popped up with a quick search. It mentions using a volt sensor if you wanted to keep the dash light.

http://www.superchevy.com/how-to/additional-tech/1801-upgrade-your-gm-charging-system-with-a-one-wire-alternator/

[Dynamo Dan]

Thanks. That was the one I had saved previously. Easy enough to do it that way. I could also do some creative wiring since the VR is history anyway and use the terminal off the alt to trigger the light using the old harness to the VR and some splicing at the VR plug so I'd have a key trigger and the light trigger going down the original. Don't know if it's copacetic but it should in theory work. Then I'd just use 8 awg to the Battery terminal at the horn relay/ buzzer. Just wanted to see if anyone has done the swap. Figures I should of thought ahead as I rebuilt the forward harness, relayed headlights, replaced the engine harness added the electric fans, fuel injection etc and looked every thing up. Lol now I've got to cut it all apart. Lol!! 

[jft69z]

Look thru all of Mark's stuff here. Lot of good theory and suggestions, plus he makes a good case why the 3 wire alternator is actually better than a 1 wire. Seems like GM engineers put a lot of thought into the charging system, wire lengths, etc. That being said, I still ended up with a 1-wire, partially because the new harness supported that anyways.

http://www.madelectrical.com/electrical-tech.shtml

[Dynamo Dan]

The diagram above worked perfectly. I just depinned the regulator connector and made jumpers to jump the wires and takes over them. That way down the road if someone wanted to change it back I didn't modify the wiring. Since the wires are only an exciter wire and light now minimal load is carried. But now with the big alternator in there at an idle 14.3v with both fans running. It hardly moved off if 14+ even cruising. A sneak peek of the car. Pretty much wrapped up now.