GM 1 Wire Alternator

[REB6PK]

Battery not charging.

When I received my car back from its long restoration project, we noticed the trunk battery was not charging. Since we are using a motor plate, they decided to go with the 140 amp GM 1 wire alternator so it would fit. They used an electronic voltage regulator that looks like the orginal old style for looks. The factory plugs are installed to the voltage regulator and the wires are hot. A new reproduction factory big block under hood wiring harness was used. We are running a MSD ignition system. The alternator is grounded from the back stud to the chassis or maybe the engine block. I am not sure. Will have to double check.
The motor is an all aluminum indy cyclinder head motor. It only has one ground wire from the cowl to the aluminum cyclinder head on the driver side. The bolt hole in the head for the passenger side faces the front of the car, so another ground was not attached.
The battery is in the trunk like the A990's used with the long cables running to the junction block on the driver side.
I am not a electricial person, so help is greatly appreciated.

 

[Ray70Chrg]

Don't know how much I can help but a couple of things stand out. 1. Doesn't that alt. have a internal reg. built-in and if so why is the old style reg. hooked up? 2. you said that Alt. stud is grounded? An I wrong about these questions.

 

[REB6PK]

They installed a factory looking alternator on the firewall just for look, but maybe we need to not hook up the factory wiring to it.
This alternator does have a internal voltage regulator.
I was wrong on the black wire connected to the stud on the back of the alternator.
It goes to the power junction block on the driver side, which the battery cables connect to.
Does not appear the alternator is grounded with a seperate wire.

 

[Mike67]

One wire has its own regulator, I'm pretty sure. That may be your problem.

 

[REB6PK]

We are going to try this weekend making a ground wire for the alternator to the engine block and might gut the voltage regulator and hook up the factory wires just for looks. Would like to keep the voltage regulator on the firewall for looks, but if it is necessary to take it off then we will. What do you do with the two wires that connect to it?

 

[Rusty 72]

If its internally regulated and its a one wire you just go from the alt to the starter relay or battery. That one wire alt does need a ground though. You can keep the external voltage regulator and just cut the wires out of sight if you want it for looks.
The ground for an iron block is at the back of the passenger head like you describe.
I have a one wire alt and don't use any of my alt wiring. I also use an MSD box so I had a lot of wires I wasn't using, I just removed all those wires from the bulkhead to clean things up.
Good luck

 

[REB6PK]

Thanks for your help!

 

[Frankb]

Rusty is correct. If using a factory wire harness with a one wire alt then there will be wires that are not required to make things work. On my car I run a 4 guage wire from alt to start relay. Thats it. I would run a 4 gauge wire from engine block to chassis. Two would be better. You do not need to ground the alt but a lot of people do. It will work either way. By junction block do you mean starter control relay? I would run a 00 guage cable from battery to starter then 4 gauge from starter to start relay. Run ground from battery to chassis. Use a 00 cable.Depending on what MSD system you are using you may be able to eliminate balast resistor and coil wires.
Frank

 

[REB6PK]

Thanks guys for the help.
We ran a ground from the back of the alternator to the bolt that the motor plate uses to connect to the frame and it works now.
What we did on the hot, blue wire that runs from the factory harness to the voltage regulator and to the ballast restistor, we traced it back to the bulk head and disconnected it so it is no longer hot.
Everything works good now.

Randy