'66 Barracuda having some charging issues

With these 40+ year old charging systems, it can be hard to tell what has been changed before you got the car.

We will assume the regulator is the original 2 wire type, and that your alternator has a single wire connected to a push on connector - as well as a large gauge wire bolted down on the output stud.

To full field the alternator for testing, you would remove the small (usually green) wire from the push on terminal on the alternator. the jumper wire goes from the terminal on the alternator where you removed the small wire to the output stud on the alternator. You do not jump the green wire to anything.

Doing that test will cause the alternator to produce it's maximum output. If you do not see more than 15v doing that test the alternator has a problem.

If you see 15v or more, then the alternator is capable of charging the battery. You may have a bad regulator or a wiring problem.

B.