Join Date: Aug 2013
Location: South Texas
Bronco Info: 1988 EB 5.0, AOD, Limited Slip Front Diff, 32x11.5x15, Stock Suspension
I put in a 3G for a 95 T-bird that I bought re-man for ~$75. The old pulley fit too loosely on the new alt. shaft and there were interference issues that would require shims and stand-offs to get it right. Rather than horse around with that I just bought a new stock pulley for the T-bird alt. Pulley goes right on using the old nut, a little grinding gets the larger case alt. onto my 302 and a little wire harness fabrication and fuse mounting later everything is in place. Works great, charges nicely even under load, but now there's a belt squeak. Almost always a loud squeal on start up and a consistent squeak for the first 10 minutes until everything gets nice and warm. I put on a new Motorcraft JK-6916B belt and had no change at all.
The new pulley is ~2.75" in diameter where the old one is just over 2". After doing a little basic trigonometry I figure I've added about 0.75" of extra belt length because the belt only contacts about 1/4 to 1/3 of the alt. pulley. [delta Circumference = pi * delta Diameter * proportion of contact] if you're keeping score at home. Also the alt. pulley is now in a slightly different location which probably adds 1-2" of belt travel. For the record the tensioner is not maxed out and I'd prefer not to replace it because I'm a cheapskate. I'd rather just put on a slightly longer belt, but how much longer?
I'm thinking of getting a JK6-936, 2" longer. From what I gather the first digit means 6 ribs, the next two, 93, means 93 inches and the last means 8ths of an inch, as in 93 and 6/8 all together.
Would anyone like to chime in, hopefully steer me straight?
This too shall pass