Hi...I have a 70 chevelle external reg. I finally got my amp gage working after installing a new harness. My problem, when I run the eng the gage shoe very little movement, turn on headlamps goes to discharge, turn on A/C and fan high major discharge. When I reve eng seems to go up a bit...is it the alt reg or both how do you test?

Steve:confused:

Also, can anyone tell me what size alt should be in the 70 396 with a/c

The easiest way to test the alternator is just to remove it and take it in to a good local auto parts shop that has a tester.

You can use a meeter to test for output of 14.xx volts at the battery, but it's still best to have them test it under load. They can help you test to see if it's the regulator or if the alternator just can't do the job anymore.

If you are going for a stock look for shows that will be judged for originality, then you need to worry about exact match, but otherwise, you might want to consider an upgrade if you want to add on high demand accessories.

Steve

Steve,

At least a 63 amp alternator. Some may even tell you to go for a 100 amp, depends on what your power requirements are, big stereo, big ignition system, couple of cooling fans, etc.

Hi...ok I am having tested. Can I run a 63 or higher on an extenal reg?

Steve

Hi...ok I am having tested. Can I run a 63 or higher on an extenal reg?

Steve
Yes, no current flows though the regulator so the the output of the alt doesn't matter as long as it's an external regulated alt.

Hi...ok I am having tested. Can I run a 63 or higher on an extenal reg?

Steve

Personally, if you want something higher than 63amp, i would convert to a internally regulated alternator. The conversion is very easy and they don't have the issues externally regulated systems have.