alternator belt - 70 amp??

[lytemup]

in trying to buy a replacement for my (81) alternator belt, i've notived "quantaproducts" lists 2, w/ and w/o 70amp generator. how do i know which i have? i couldn't find it in any options list, so was this a st louis/ BG mid year change?
thanks!

 

[Dave L.]

I ran into the same problem last year when I replaced the ALT.mine turned out to be the 70.It had a 70A stamped right on the housing.The 70a alt is visibly larger than the 63A.Also,I beleive the 70A uses an aluminum lower mount bracket.

 

[kustomvette]

alt.

i took mine off and took it to advance auto and they ran the numbers and tested it for free . ende up with a 100 amp alt. i bought off an alt.rebuilder on ebay because of the new composite lamps and amp,stereo and aux. lamps. works great at 14.0.....joe

 

[Eric]

One more thing you'll want to be aware of, the pulley size was reduced on most of the remanufactured and newer alternators to help maintain power at lower RPMs. I encountered this when I replaced mine. If this is the case, you have two options: go with a slightly larger belt (it was out of the range of the adjustment bracket with the original belt) or have the place you bought it switch the pulleys. I would suggest sticking with the smaller pulley since they reengineered it for a reason so you may as well take advantage of it.

 

[Nut]

What's interesting in all this is when my alternator (81) went out last year, I checked the manuals and found that an (85 amp) is listed as the stock alt. I have never heard of anyone with a 1981 that ever had a factory 85 amp alt. Mine was the original alternator and it was a 63 amp. I replaced it with the (physically larger) and correct 85 amp model. My pulley was slightly larger and I had to do a little creative engineering to get it bolted in place and belt tightened. But the V belt was the same fit for both.
Go with the higher rated amp. It's worth it.

............. Nut

 

[lytemup]

70A

well thanks for the tips, i checked on the housing, and there's a 70A on there. maybe i got the 70 over the 53(?) since i think i have all the power options. anyway, thanks