Upping the boost on my 8-71 blown big block
#1
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Join Date: Aug 2011
Posts: 5
Upping the boost on my 8-71 blown big block
Here's the set up. 468 BBC. 8-71 with 2 750's. Jetted square with 72's. 8 to 1 pistons. 61 top pulley, 54 bottom, for about 9% under-driven. Runs on 93 octane pump gas. Chassis dyno'd at 461 hp, 420 ftlb tq. I'd like to kick up the boost, without having to go to race gas. I figure swapping the pulleys would be way too much, even jetting up the carbs. So, what size top pulley can I go to? And how much higher on the jets?
#6
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Upping the boost on my 8-71 blown big block
Is there any "rule of thumb" as far as jetting increase, when changing pulleys from 54-61 (9% under) to 54-54 (1 to 1)? Like, maybe, one jet size per two teeth or something? Just some sort of starting point, so I don't melt pistons trying to find the right combo!
#7
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Join Date: Jan 2012
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Re: Upping the boost on my 8-71 blown big block
Originally Posted by f35rocket
Is there any "rule of thumb" as far as jetting increase, when changing pulleys from 54-61 (9% under) to 54-54 (1 to 1)? Like, maybe, one jet size per two teeth or something? Just some sort of starting point, so I don't melt pistons trying to find the right combo!
Start with jetting that should put you rich and then lean it out to taste . . Kinda like making Chile . . .