When I got my '86 GT several years ago, I soon got sick of the alternator belt squealing everytime it rained. Sure, I could tighten the belt, but that was always a temporary
repair as two weeks later it would squeal again. I bought Dodgerunner's auto belt tensioner
and was very
happy with it. Solved the problem completely. The belt never squealed again.
Fast-forward... and a month or so ago I acquired an '88 Formula. I want to sell the 86 GT, so I figured I'd transfer the belt tensioner over to the Formula. I noticed the pulley on the Formula's alternator had an extra rib, but after researching here, I learned that installing the belt towards the inner
ribs on the alternator would work fine in regards to belt alignment.
However, I noticed something just didn't seem right when I installed the alternator belt on the Formula. It seemed like the auto tensioner pulley was closer to the crank pulley than what I remembered on the GT. There was very little space between the two pulleys. It was almost like the belt was now too long.
And then a couple weeks later, the belt started squealing! What the heck...!
Anyway, to make a long story short, I discovered that not only was there an extra rib on the Formula's alternator pulley, but also that the diameter
of the Formula's pulley was smaller (2 3/8") than the one on the GT (2 5/8").
These pictures will show the difference.
The top pulley is flipped over so that the pulleys are sitting outer end to outer end.
I now have a larger pulley installed (taken off a junk alternator I had sitting around) with the correct number of ribs. The larger alternator pulley will result in less drag on the engine (alternator still charges just fine, even at idle), and the replacement pulley is much
lighter as well. (Different type of construction.) It was a win-win situation to replace this pulley.
And the belt doesn't squeal anymore!