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pulleys


sendo

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changing pulleys to add a/c to my car and ran into a problem with the new crankshaft pulley hitting the fan pulley. cant find a 3 groove pulley that is the same size as the original 2 groove. is there one or is there a different size fan pulley?

 

opulley.jpg

npulley.jpg

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I checked my stock lower pulleys from the 72 402. I have 2 of them kicking around here, (one I got from a dealer when I built an older Monte, different part numbers, but same pulley dimensions). Both are the same 7 11/16" as you have. The water pump pulley that was on the car originally is 6 3/16" diameter and has a GM part # 3995631AO.  At least on my car, those are the stock pulleys used on a BB A/C engine. What diameter is your WP pulley?

The WP pulley listed above seems to fit both small & big blocks.

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Parts book doesn't show size but it looks like it fits all the way up to 1975

 

70 Chevelle w /A ir Cond. (454),
70 Pass. w/C.A.C., A.T. (454),
70 Pass. w/Acc. Air Cond. (454),
71-72 All w /A ir Cond. (454),
73-75 All (454) ............................................. 3 9 3 7 7 8 7  1 12.90 PULLEY (3 groove) (Note 1)
NO TE 1 N o t u s e d o n m o d e ls h a v in g A c c . A i r Cond. a n d 2 .5 6 o r 2 .7 3 a x le ra tio .

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2 hours ago, jft69z said:

I checked my stock lower pulleys from the 72 402. I have 2 of them kicking around here, (one I got from a dealer when I built an older Monte, different part numbers, but same pulley dimensions). Both are the same 7 11/16" as you have. The water pump pulley that was on the car originally is 6 3/16" diameter and has a GM part # 3995631AO.  At least on my car, those are the stock pulleys used on a BB A/C engine. What diameter is your WP pulley?

The WP pulley listed above seems to fit both small & big blocks.

don't have time to take it off till next week, but just measuring from the top of the wp shaft its bigger then 6 3/16.

so that may be the problem

wppulley.jpg

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2 hours ago, 1970mcss said:

Parts book doesn't show size but it looks like it fits all the way up to 1975

3 9 3 7 7 8 7        1 12.90 PULLEY (3 groove) (Note 1)
 

That's the part number I have for the original lower 3 groove on my '72, except with an "AC" suffix.

The superseded part number for the same sized 3 groove lower that I also have is 14025185BN

Can you make out a part number on that pulley Rosendo?

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Well that's good, mystery solved. Now maybe get one of those 3995631AO  pulleys listed for an A/C car from ebay & you're good to go. There's at least a dozen to choose from, all in the same general price range.

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