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So now its not blazing hot in the garage its time to run down some obnoxious problems. In this case, horrendous alternator belt squeal upon start up. I removed belts to chase the issue and its the alternator belt that absolutely screams upon start up. Come to find out the pulley on the alternator does not come close to aligning with the outer most pulley on the power steering pump per the belt schematic. Can anyone confirm if my alternator mounting brackets are in the correct orientation? As far as I can tell they are but as you see in the pics below the belt is way off by about 1 pulley width from where it should be. The solutions I'm thinking are to A) find a double V alternator pulley or B) triple V crank pulley and a longer alternator belt and wrap the alternator belt mimicking the power steering belt routing. Option B seems dumb. The belt stops squealing eventually but I can tell its starting to eat away at the belt (fine black particles everywhere. Probably isn't doing the bearings on the alternator and p/s pump much good either. Note V pulley lines up with inner most P/S pulley groove. Should line up with outer most P/S pulley Bracket Orientation Correct?
A couple of things to consider:
1. Yes.... you should align that a little better ..... and
2. Is that a brand name belt? I didn't believe the napa guy when he told to buy a brand name belt....but I bought one.... sure enough. No more squealing and not overtightened.
3. Can you find a deep groove pulley. That sure doesn't look like a deep groove pulley??? Where did you get that pulley?
Not sure and I only have a shitty picture but mine looks a bit deeper. I can get another picture if you want to see one......
You are correct.
It should line up with the outer PS pulley groove.
And if they do not line up almost exactly, they will squeel badly.
You need a different alternator pulley.
It has a 1/2" space between the groove and the alternator.
This one is correct for BBs with PS. https://www.zip-corvette.com/64-74-a...-1-4-wide.html
Yup. Our BBs came with a pulley that had ~1/2" space between the groove and the alternator fan. Otherwise, your brackets look like they're installed correctly.
TexVette01
Do you have your old alternator pulley?
Compare it.
Pretty sure that pulley on there is NOT a deep one.... I'll get another better pic of mine and try to get a ruler depth....
Seems like your alternator mounts might be worn.... could eyeball those to see what you can do about that.
I'll get another pulley picture.
Originally Posted by TexVette01
The belt is a Gates 8322RXSS and the pulley is what came on the Powermaster brand alternator. I'm not sure how deep it is.
Last edited by carriljc; Sep 11, 2025 at 01:02 AM.
me pulley views just for comparison.
I am using the smaller pulley to maximize alternator RPM for availability of amperage at idle. I have a ton of electrical loads. The larger deep pulley is from one of my older alternators. Anyway... should give you an idea on that pulley you have. If you let us know how deep it is to the edge then the forum will more more info.
Sadly the old 63 amp alternator was removed by a shop and trashed and they clearly did not transfer the pulley over. I was unaware too that the pulley had that spacer built in to it. Going to order the correct pulley today. Updates to come!
TexVette01
What powermaster model do you have there?
Would you mind getting a pulley depth measurement to the edge (I only say for measuring consistency)? Just curious actually.
FYI- my a/c belt is slightly "off" and I don't have squealing....
There is no part number stamped anywhere on the Powermaster alternator oddly enough. Maybe it was a sticker that melted off. Unfortunately I can't find a straight edge to measure the inside diameter of the Powermaster pulley.
I did receive the big block pulley today. It doesn't fit on the shaft of either the Powermaster or the Summit 10si I have sitting around. Going to try heating it up and getting it on the shaft. Its always something; nothing ever fits correct these days.
Here is the specs on a factory BB alternator pulley if it will help you out. It went right on my PowerMaster CS144 style 200 amp alternator.
Just be aware that if you are running a high amp (170+) alternator, this big 3” pulley won’t let the alternator spin fast enough at dead idle and it won’t charge well unless you crank the idle speed up to about 900+ rpms. (1 wire style alternators anyway).
TexVette01
You should not have to do that. I've swapped multiple gm pulleys on multiple gm alternators and they have always fit snugly but perfectly sliding on. And I've swapped from serpentine to single groove pulleys on both my 140-amp CS-144 and my 145-amp DR44G
If you do go at it...I would recommend just doing some emory cloth until it slides on...hell put the emory cloth on a drill.......
Hopefully, at least comparatively, it is deeper than what you had.
Originally Posted by TexVette01
There is no part number stamped anywhere on the Powermaster alternator oddly enough. Maybe it was a sticker that melted off. Unfortunately I can't find a straight edge to measure the inside diameter of the Powermaster pulley.
I did receive the big block pulley today. It doesn't fit on the shaft of either the Powermaster or the Summit 10si I have sitting around. Going to try heating it up and getting it on the shaft. Its always something; nothing ever fits correct these days.
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What year is your car, and what does the AIM show.
I have the same brackets and mine comes off the outer pulley slot from the power steering but mine is a 68
Thanks that does help a lot. The pulley I ordered from Top Flight doesn't fit; the shaft hole is too small (maybe the only reason they had one and nobody else does). I heated it up in the oven and even then i won't slide easily on the alternator shaft. Zip says the big block pulleys are backordered until October (wtf) and Corvette Central is probably the same since it won't even let me order the damn thing on the webpage. I guess I'll have to wait on the backorder nonsense. I'll be checking the measurements if/when I receive it to make sure they are where they should be.
Also my idle is set to 900rpm due to the cam in the engine.
Edit: just checked that old auction website and people are selling OEM big block pulleys for over $200 each!
Also, noticed the OEM pulleys have a key way notched in them. I wonder if these new pulleys really are press on?
Last edited by TexVette01; Sep 13, 2025 at 07:43 PM.
Thanks that does help a lot. The pulley I ordered from Top Flight doesn't fit; the shaft hole is too small (maybe the only reason they had one and nobody else does). I heated it up in the oven and even then i won't slide easily on the alternator shaft. Zip says the big block pulleys are backordered until October (wtf) and Corvette Central is probably the same since it won't even let me order the damn thing on the webpage. I guess I'll have to wait on the backorder nonsense. I'll be checking the measurements if/when I receive it to make sure they are where they should be.
Also my idle is set to 900rpm due to the cam in the engine.
Edit: just checked that old auction website and people are selling OEM big block pulleys for over $200 each!
Also, noticed the OEM pulleys have a key way notched in them. I wonder if these new pulleys really are press on?
No the aftermarket pulleys will slide right on/off the alternator shaft.
Measure the hole ID of your new pulley, it should be around .6” or so…if not, open it up a little with some Emory cloth or a Dremel tool with a sanding wheel. It won’t take much.
Normally a big block repro alternator pulley will slide right on any GM large frame alternator. (10si, 12si, CS130, CS144)
The customer service representative’s at Power Master are awesome.
They may be able to identify the alternator you have on your big block by sending them a couple photos and they can confirm whether or not it is the correct alternator for your car.
You have no idea if the shop who installed the alternator installed the correct one or not.
If the alternator is correct, I would ask Power Master if they offer the correct pulley.
Next, inspect your brackets while you have the alternator removed.
The alternator bracket on my big block was cracked clean through and put the alternator at a slight angle.
One last thing, when you tighten The alternator/bracket bolts make sure however you apply tension to the belt, that the alternator stays straight.
Many people use a large screwdriver or bar to pry the alternator back while they tighten the bolts.
This can cause the alternator and pulley to be slightly askew causing wear on the belt and possible squealing.
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Our BBs came with a pulley that had ~1/2" space between the groove and the alternator fan. Otherwise, your brackets look like they're installed correctly.
Big Block Belt Dilemma
