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alternator belt - 70 amp??

L

lytemup

Guest
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!
 
D

Dave L.

Guest
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.
 
K

kustomvette

Guest
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
 
Joined
Jun 5, 2001
Messages
2,231
Location
Northern Virginia
Corvette
71 Conv. (Sold) / 98 Pewter Coupe (Sold)
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

Well-known member
Joined
Oct 15, 2000
Messages
890
Location
Bowie, MD
Corvette
Vette-less for now
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
 
L

lytemup

Guest
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
 

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