Fendermb4

In an effort to clean up my engine compartment, I did the following:

1. Replaced alternator with new one, which is internally regulated.
2. Removed external voltage regulator. Jumped wires together as shown here:
http://www.ecklerscorvette.com/corve...1963-1968.html
3. Wired those 2 wires at the top into the plug for the new alternator, with the blue wire on the right.
4. I unhooked the wires at the horn relay on the 2 terminals and re-connected them.

The symptoms I now get are:
1. The alternator gets hot, even when the car isn't running.
2. The ammeter jumps around like crazy when revving the car. My Ammeter used to pretty much stay in the middle all the time. Now it stays in the middle at idle, but goes up and down with revs, more or less using the entire sweep of the gauge. Is that normal? Should the ammeter move a lot? Or more or less stay still?

I've measured 12-14v at the alternator positive post, which I can read using the alternator body or the engine block as ground. I have continuity between the engine block and the alternator body/alternator ground wire. I do not have continuity between ground and the positive post. The horn works.

I don't understand what those 2 wires at the top of the alternator do, so I'm not sure if those being reversed or wrong could be the issue. I'm also unclear on if the problem could be jumping the external voltage regulator wires, some of which ultimately connect to the top of the alternator.

I don't know what to test next or how to diagnose it. Any thoughts?

Thanks!

Garys 68

Someone over at the Olds forum just went through this with that stupid connector.
I'm assuming you have a 3 wire alternator. One is the 12V output (big one on the back). The 2 small posts are the 1) excitation (key switched 12V, tells the alternator to charge) and 2) sensor (monitors the voltage at the distribution point).
Lose the external regulator wiring. Anything spliced in there can screw it up.
You can look up online which post is excitation and sensor. The excitation can be hooked to any switched 12V source. The sensor wire goes to the distribution point. That would be the horn relay connector on your car.
If that does not fix it, your alternator is bad. An ammeter needle quickly going back and forth is an indication of AC voltage due to a bad diode.

Fendermb4

Ahh, thanks Gary, that helps a lot.

Can anyone suggest a good 12v key switched source in that wire bundle over by the alternator?

Garys 68

I stripped out the harness on my 68 and went with a generic aftermarket. But IIRC, the original excitation wire was off the ignition aux feed to the radio. You might be able to trace it back from the wire that connected to the old regulator.
Do not use the feed to the coil. That goes through a ballast resistor wire.

Fendermb4

I had grabbed the coil feed wire, so thanks for the note on that.

It looks like this is all sorted out, thanks a lot Gary!