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What size pulleys for endurance racing? |
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Hurst390
AMC Addicted Joined: Apr/20/2008 Location: secret Status: Offline Points: 5822 |
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Posted: Feb/04/2012 at 3:16pm |
What size pulleys do you guys run on your AMC engines for cooling...stock? underdrive? tell me what works in road race or circle track..Thanks |
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SC/Hurst Rambler
11.62 120 100% Street Legal |
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His68Hers71
AMC Fan Joined: Oct/13/2009 Location: Los Lunas, NM Status: Offline Points: 20 |
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There are many people with more knowledge than me on this form. But I stay stock had a underdrive once and kept eating up water pumps. Don't understand why maybe to much torque even though it was turning slower. Run factory 71 pulleys no problem at 5 plus grand.
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amcglass
AMC Addicted Joined: Dec/11/2011 Location: NW Ohio Status: Offline Points: 2588 |
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not trying to be a smartie pants here but eating up waterpumps could be in the tightness of the belts. Ive seen it many times if the belt is TOO TIGHT plus the torque causes issues just food for thought |
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Javmanpres
BBG Mark Donohue 401 74 Jav/AMX 71 Matador 2dr sedan delivery wagon 1902 Rambler Runabout 70 T/A Javelin |
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Hurst390
AMC Addicted Joined: Apr/20/2008 Location: secret Status: Offline Points: 5822 |
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Thanks for the replies..I Spoke with Barry and he gave me a baseline to start with...
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SC/Hurst Rambler
11.62 120 100% Street Legal |
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74Bubblefender
AMC Addicted Charter Member Joined: Jun/29/2007 Location: The AMC form Status: Offline Points: 2589 |
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From what we have sold in the last 10 years, 20% crank seems to be the norm on guys who are street racing. I would say maybe 80 racers out there in the world that have ordered 20% just for endurance.
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We are just about to forge new AMC V8 crankshafts.. please check here
http://www.bulltear.com/forums/showthread.php?19564 |
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Hurst390
AMC Addicted Joined: Apr/20/2008 Location: secret Status: Offline Points: 5822 |
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Several years later....I tried a reduction crank pulley and it ran cool at WOT but on yellow flag's it heated up. I found using chevy 1-1 pulleys is the best all around set-up for cooling. It runs 190 all the time
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SC/Hurst Rambler
11.62 120 100% Street Legal |
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304-dude
AMC Addicted Joined: Sep/29/2008 Location: Central Illinoi Status: Offline Points: 9082 |
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oddly enough pulley sizes are scattered on who uses what on their engines.
NASCAR R07 engines from ECR used a dual stage 6.4" water pump pulley with a 7.4" diameter for steering pump drive. Assuming 8k to 9k RPM ranges are 85% of operation during a race, water pump will be not over driven. Most race power steering pumps have variable pressure settings. So no need to under drive with a 5.5" pulley. Most NASCAR Ford engines use 5.5" or abouts, on the water pump pulley with the second stage to the power steering pump of the same diameter. Assuming an aluminum C-III pump is used or they are using lower pressures on their steering pumps, and sticking with It. For myself, I am under driving a police alternator which at stock will produce 100A @ 1500 RPM. Being under driven 80A should be at 1500 RPM. An alternator will always need under driven if going all out above 80% of the time. Water pump can be 1:1 as there is a limit to flow effecting pump spin. Once RPM is too great pumping effect is wasted into force against ability to spin, thus effecting engines efficency. |
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71 Javelin SST body
390 69 crank, 70 block & heads NASCAR SB2 rods & pistons 78 Jeep TH400 w/ 2.76 Low 50/50 Ford-AMC Suspension 79 F150 rear & 8.8 axles Ford Racing 3.25 gears & 9" /w Detroit locker |
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