1984 In A 65 / 302 Electrical Problem

Mine does the same thing. Its just low output and voltage at idle. Rev the engine around 1200 rpms and it steadies out.

You didn't say what kind of alternator you have. If it is a stock one then I stand by what I said.

If you want it to go away, upgrade to a ford 3g alternator. I believe you can find them in 1 (internal regulated) and 3 wire (external regulated like stock was).

The 3g alternators can put out about 75+ amps at idle (for a 100 amp rated one).

You can also put a smaller alternator pulley on.. But I don't think they are easy to find as its already pretty small, and you can possibly be over speeding the alternator at high(er) RPMs