Ammeter swings wildly, weird alternator wiring

[RustyRatRod]

Mine did as well, and I always had a square back.
In my case I rewired the regulator sense wire (blue wire on the regulator) through a relay direct to the positive post on the starter relay.

In the run position the relay closes allowing the regulator to see direct battery voltage instead of it running out through all the other ignition and ballast resistor wires.
The regulators voltage sense wire is basically a straight shot to battery pos.

That eliminated bouncing.

I guess if I idled her down a little it might make the headlights fluctuate, but she doesn't like idling much below 900. Old slant 6 has a bunch of cam in it. lol

 

[Dana67Dart]

Bad diode in the alt can cause that.

Take it to parts store and have the test it in the vehicle

 

[RustyRatRod]

Bad diode in the alt can cause that.

Take it to parts store and have the test it in the vehicle

If he can find someone who knows HOW.

 

[TrailBeast]

Bad diode in the alt can cause that.

Take it to parts store and have the test it in the vehicle

As can a weak battery.