Re: Are there any "small" OEM BB crank pullies?
[Re: BSB67]
#2722516
12/08/19 12:29 PM
12/08/19 12:29 PM
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Joined: Jan 2003
Posts: 15,439 Val-haul-ass... eventually
BradH
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Taking time off to work on my car
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OP
Taking time off to work on my car
Joined: Jan 2003
Posts: 15,439
Val-haul-ass... eventually
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Not sure what diameter the Moroso is, only that it says a 30% reduction in pulley speed, IIRC. My brain hasn't shifted into calculator mode to reverse-engineer the diameter. .
Reduction will be directly proportional to diameter. Diameter? 70% of 6.25 is only about 4.3... unless the standard factory pulley is actually 7+".
Last edited by BradH; 12/08/19 03:04 PM.
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Re: Are there any "small" OEM BB crank pullies?
[Re: AndyF]
#2722518
12/08/19 12:34 PM
12/08/19 12:34 PM
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Joined: Jan 2003
Posts: 15,439 Val-haul-ass... eventually
BradH
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Taking time off to work on my car
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OP
Taking time off to work on my car
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Val-haul-ass... eventually
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At 3500 rpm cruise you could use a smaller pulley without any trouble. My guess is that the factory designed the water pump to be really effective in the 2000 to 2500 rpm range so you are probably overdriving your pump a little right now. A smaller crank pulley might improve cooling on your setup. I was thinking pretty much the same standard RPM range; 30% slower than 3500 is 2450...
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Re: Are there any "small" OEM BB crank pullies?
[Re: BradH]
#2722534
12/08/19 01:00 PM
12/08/19 01:00 PM
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Joined: May 2011
Posts: 625 Oakville, Wa
HOTMOPR
mopar
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mopar
Joined: May 2011
Posts: 625
Oakville, Wa
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67 Barracuda, 470" B, Glide, FuelTech FT600, Precision, Ptc, QA1, Calvert, Smith racecraft, Afco, Dana 60. 275 radials
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Re: Are there any "small" OEM BB crank pullies?
[Re: HOTMOPR]
#2722560
12/08/19 02:39 PM
12/08/19 02:39 PM
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Joined: Jan 2003
Posts: 30,989 Oregon
AndyF
I Win
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I Win
Joined: Jan 2003
Posts: 30,989
Oregon
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Re: Are there any "small" OEM BB crank pullies?
[Re: BradH]
#2722565
12/08/19 03:06 PM
12/08/19 03:06 PM
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Joined: Feb 2005
Posts: 4,310 Prospect, PA
BSB67
master
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master
Joined: Feb 2005
Posts: 4,310
Prospect, PA
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Not sure what diameter the Moroso is, only that it says a 30% reduction in pulley speed, IIRC. My brain hasn't shifted into calculator mode to reverse-engineer the diameter. .
Reduction will be directly proportional to diameter. Circumference, not diameter. 70% of 6.25 is only about 4.3... And 70% of circumference still results in 4.3" diameter. Pulley speed, circumference and diameter are all proportional. So either Moroso made an error, or their pulley is 4.3, or they started with a different pulley diameter for the claimed 70%. FWIW, the crank pulleys I have here range from 6.5 to 7.25.
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Re: Are there any "small" OEM BB crank pullies?
[Re: AndyF]
#2722589
12/08/19 05:35 PM
12/08/19 05:35 PM
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Joined: Sep 2003
Posts: 421 montana
BANDIT
mopar
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mopar
Joined: Sep 2003
Posts: 421
montana
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Years ago, MP used to sell March pulley sets. When they quit, they were selling them off cheap. I picked up a few different sets with that smaller lower pulley and have used it on a couple of street cars. They are quality pieces.
64 Dodge Coronet 440. In progress 1998. Dodge Avenger. 8.35@165. 4400 DA 250” Neil and Parks Slip Joint. 7.36@183. 4600 DA 242" Mullis Dragster. 6.90@ 200mph
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Re: Are there any "small" OEM BB crank pullies?
[Re: BANDIT]
#2722730
12/09/19 11:51 AM
12/09/19 11:51 AM
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Joined: Jan 2003
Posts: 13,351 Marion, South Carolina [><]
an8sec70cuda
I Live Here
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I Live Here
Joined: Jan 2003
Posts: 13,351
Marion, South Carolina [><]
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I used to run the small Moroso crank pulley w/ a belt driven water pump setup on my 14:1 Indy headed 440. That was years ago in my cuda, ran 10.40s, but ran great on the street. No cooling issues whatsoever, just went through a lot of C12, lol.
CHIP '70 hemicuda, 575" Hemi, 727, Dana 60 '69 road runner, 440-6, 18 spline 4 speed, Dana 60 '71 Demon, 340, low gear 904, 8.75 '73 Chrysler New Yorker, 440, 727, 8.75 '90 Chevy 454SS Silverado, 476" BBC, TH400, 14 bolt '06 GMC 2500HD LBZ Duramax
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