Alternator School

2/25/01 Alternator School

I spent some time on the Internet trying to learn more about alternators. First, I wanted to determine if my alternator is a internally, or externally regulated alternator, and second, I wanted to make sure I was wiring my car in the best possible way.

After some searching, I found the Delco-Remy web site, but I would have to call them on Monday to check my part number. Looking around some more, I found some pictures of some alternators and I discovered that I probably had an externally regulated alternator. Since I would need an internally regulated alternator, I would have to buy a new one.

My next job was to find some more information on wiring up my alternator. Some confusing information between the article in “Auto Restorer,” and other publications needed to be clarified. The “Auto Restorer” article shows two wire modifications while many hot rod web sites mention wiring only one wire for an alternator. After some research I found the reason for the discrepancy.

GM (delco remy) one wire, internally regulated, alternators actually have three connections on them. One goes to the battery, one is labeled “F” and the other is labeled “S.” A normal GM alternator needs to be “energized” on its “F” lug in order for it to begin charging, but there is an alternator that has a “self energizing” regulator that hot rodders are using. These alternators are modified GM alternators that “self energize” by turning on when the alternator is spun. The circuit is also turned off when the alternator (i.e.. engine) is stopped. This eliminates the need to wire an power feed from the ignition switch. I also found that you can buy these modified alternators at JC Whitney.

Here’s a web site that might help make more sense if you’re still confused.

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