voltage fluctations

I think your my new best friend LOL. I will give those a try. I did run a 4 gauge wire from the alt to the battery and also a good 4 gauge ground so that should not be the issue. I do have another alt but that is another story LOL.
It came as a spare with a car I picked up, thing looks brand new. I installed in my car and it over charged into the 16s. I had it tested and they said it was good. Put the old one back on..a year later I tried it on a different car and same thing 16 volts at high idle. Took it to another rebuilder for a test and they said it was ok nothing wrong with it..so it is sitting in a box ion the garage..funny thing is it might work in this car LOL.
Thanks very much 67Dart273
AL