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Pulley/Belt Configuration on 68

J

jonward786

Member
My 68 was an AC/PS car, so it has a 2 groove WP pulley and a 3 groove crank pulley. I removed the non-functioning AC compressor so I'm currently not using the larger 3rd groove on the crank pulley.

After upgrading the alternator to a 3g i'm getting excessive belt squeal and decided to run a dual groove pulley on the alternator. Question is this:

Originally the belt running the PS pump went around crank - WP - PS. Now I need that 2nd equally sized crank pulley for the alternators second belt, so...can i move the PS belt to the larger crank pulley that the AC belt used to be on and just run the PS directly off the crank with no other intermediary pulley? Since the groove on the crank pulley that was originally for the AC belt is larger than the other 2 grooves on the crank pulley, will this increase in RPM for my PS pump do any damage?
 
You can do it that way if you chose to. Is the outermost groove on the crank wider than the other two?


I'm running a 160 amp 3G with a single groove pulley and have zero squeal. Are you sure you have it lined up right? I had to bump mine out about 1/8th from stock to get a straight alignment. Alignment is most likely cause of squealing from what I've read.
 
Not wider, it would use the same size v belt. But like i said that third groove on the crank is about an inch larger in diameter than the other two grooves. Maybe the AC needed to be at a higher RPM

I did check the alignment because like you I read it can be a cause of squeal and it looks as straight as it can get. If it is off, I can't see it. My belts may have lost some of their silicon content over time and maybe aren't gripping very well. Either way, Powermaster says that if you're going to attempt to use a single v belt the belt has to be VERY VERY tight, and I don't know how i feel about that considering alternator bearing longevity. I think 2 belts so they can be a little looser may be better in the long run.

But man, after only 5-10 seconds of running and hearing that belt squeal, i damn near burned my finger on the alternator pulley. That thing was HOT. I bet it would have melted the belt after several minutes.
 
"jonward786" said:
Not wider, it would use the same size v belt. But like i said that third groove on the crank is about an inch larger in diameter than the other two grooves. Maybe the AC needed to be at a higher RPM
Click to expand...

Larger diameter crank drive pulley will produce a lesser RPM to the alternator than the other two would.
 
"1497" said:
Larger diameter crank drive pulley will produce a lesser RPM to the alternator than the other two would.
Click to expand...

Not according to the instruction sheet Powermaster sent with the alternator. It's one page with a huge "WARNING" on top telling you how to calculate alternator pulley RPM.

(Crank Pulley Dia / Alt. Pulley Dia) x (Max engine rpm) = max alternator rpm

Increase the size of the driving pulley (crank pulley) and the driven pulley has to spin faster to maintain the ratio
 
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