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chevyart 04-27-2013 10:14 AM

carb setup
have a holley 750 cfm carb with a profoam center section. would like some opinions on the setup i have done on this carb. engine is going on is a 377 cu in sbc with 13.5 compr., 220 cfr afr heads, lunatti cam around 660 lift with around 207 @ .050 duration, vic jr manifold with 1 inch spacer, running 561 gears and glide and coming through traps around 78oo rpms. its an aluminum rodded engine. carb has front power valve(3.5) 78 primary jets, and 86 secondaries.. primary air bleeds are 76 and secondaries are 36. this car now suppossedly flows around 820 cfms(says mfg.)am i too high on the jetting or will this be good. had severe overheating problem last year and it was attributed to too lean jetting. and as i upped the jet size it got cooler. does this make sense. should the bigger jets be only in a bigger carb like an 850 cfm carb? thinking of removing power valve and running 86-86 in front and rear of carb.. is this too much. still have the stock 750 metering blocks and just have the front idle adjustment. i got good advice from a fellow in canada on this setup, but he thinks my front jetting ideas will make it too rich. thanks art

jmarksdragster 04-27-2013 06:30 PM

74/82 +- 2 jet sizes would be closer for most engines and a 750. Idle air bleeds should be the outer ones and 76 is fine to start with. Main air bleeds are the inner closest to the vent tubes, get some 28's in there.

chevyart 04-27-2013 08:13 PM

thanks jmark the jetting 74-82 up or down 2 sizes. is this recomendation you make still using the power valve in the front. i would think this is what you meant(to keep the power valve). art

jmarksdragster 04-28-2013 08:00 PM

Yes, start at 82 square and jet from there with both PV's plugged, 74 in front with a PV in front. This may be on the rich side, but will be a safe starting point.

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