I have a 70 convertible with a 350 and a few mod's.
A aftermarket AC was installed in the car before I bought it. I was running the car in the driveway the other day and could hear a squeek in coming from the alternator. It did not sound like belt noise either. I've talked to a couple of people and they felt the noise could be a bearing in the alternator.
Ok while I was running the car I noticed when I would turn on the AC the volt gauge on the dash would pull down more then I felt was normal. I did this a couple of times to confirm what looked like a large draw on the system. BTW the blower switch only works on the high poition.
I'm not positive what size the alternator is on the car at this time due to being away from the car but pretty sure it's not original.
What type alternator should I get for the car. I would like to get one that will wire up like the old alt, and what size should I get whether 63-70-85 amp or larger.
What if any are advantages or disadvanatges of the larger (more amps) alternator and or would a larger amp alt hurt the old orginal wiring.
I've looked at all the alternators at the summit site and now more confused.
I would consider the alternator thats got a little bling (chrome) to it to.
Thanks for any help.

A squeak could very likely be a bearing.

How much draw does the AC place on it and why do you think it's more than usual? What are old numbers vs what it is currently doing?

I can't help you much as far as what your year came with stock, but if you want to go a higher amp output you can have the alternator rebuilt for cheaper than buying new and a competent shop can restring it for more output.

Good luck,

Matthew

I just got done throwing a Powermaster in the trash, so maybe that wouldn't be your first choice if you buy from Summit.

For an easy installation you can get a stock alternator replacement for a later year C3 like a '78 and it'll be a 63 amp unit intended for stock electrical systems with A/C.

You can have your original one rebuilt to stock or you can have it rebuilt for higher output, and you can even install a later model CS130 or CS144 for even more power.

Yea, I was wondering about a later model alternator fitment.

More amps is never a bad thing.

A squeek could also be a weak brush. When did GM go with internal voltage regulators?

My guess is that stock alternator is putting out no more than 45 amps. As such, the fan on high is drawing 15 of them. That leaves 30 to run the car and any other accessory that might be on.

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A C4 Corvette alternator, CS133, is almost a direct bolt in requiring only a pulley change and an adapter for the wiring.

The CS144, 200 amps alt, is also an option but it's larger case makes the bracket and belt work a little more complex.

http://photos.imageevent.com/durango_ ... 0Alternator%20Install.pdf

Thanks for all the information guy's.
It looks like everyone is in agreement to take it to get rebuilt.
So what amp rating or out put should I ask to have up graded to. 70, 85 or a hundred be ok?
Thanks, Again.

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Stay under 100, or don't go over. The SI alternator as a platform was never designed to put out over 100 amps and the ones built for 100+ usually die as a result or they just never truly see that output. For the most part you'd have to have a LOT of auxiliary accessories and extra draw to need 100 or more.

Thanks Guy's.

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Nice write-up there D_Boy. You-Da-Man.