What size cfm should I run with a 350 with 350hp?
01-08-2001, 10:16 PM
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What size cfm should I run with a 350 with 350hp?
same as above. Thanx!!!! Oh, its a holley 650 right now. A bit much I think.
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91 Camaro RS, 305 TBI
No mods yet...Hopefully:
Convert to dual-cat with headers and Borla catback exhaust.
Edelbrock MPFI system.
RAM air hood & Z28 wing.
Z28 cam.
ABS system.
Positraction rearend with rear disc brakes.
Rebuilt front and rearend suspension with polygraphite bushings.
Strutbrace.
Rollbar.
------------------
91 Camaro RS, 305 TBI
No mods yet...Hopefully:
Convert to dual-cat with headers and Borla catback exhaust.
Edelbrock MPFI system.
RAM air hood & Z28 wing.
Z28 cam.
ABS system.
Positraction rearend with rear disc brakes.
Rebuilt front and rearend suspension with polygraphite bushings.
Strutbrace.
Rollbar.
01-09-2001, 01:46 PM
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Here's the old tried and true equation for sizing a carburetor:
(CID X RPM X volumetric efficiency(%))/3456
The formula constant assumes a 1.5" Hg vacuum drop across the carb.
So, for your 350 at 5000RPM and breathing with 100% efficiency (not likely), your engine will flow 506 CFM. Even accounting for the demand created by vacuum impulses inherent in all piston engines, your 650 Holley is just fine as long as it has vacuum secondaries.
(CID X RPM X volumetric efficiency(%))/3456
The formula constant assumes a 1.5" Hg vacuum drop across the carb.
So, for your 350 at 5000RPM and breathing with 100% efficiency (not likely), your engine will flow 506 CFM. Even accounting for the demand created by vacuum impulses inherent in all piston engines, your 650 Holley is just fine as long as it has vacuum secondaries.
01-10-2001, 11:32 AM
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Do you have stick or auto? There's always a greater risk of bogging problems with large carbs w/mechanical secondaries. But, as a prior post said, just make sure that carb is jetted right!
But, I'm biased towards vacuum secondary carbs because they are inherently forgiving when you stomp down on the gas. Hopefully, someone with 650 double-pumper experience on a 305 will offer up some advice here.
But, I'm biased towards vacuum secondary carbs because they are inherently forgiving when you stomp down on the gas. Hopefully, someone with 650 double-pumper experience on a 305 will offer up some advice here.
01-13-2001, 08:21 PM
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ok i suggest using a 600 edlebrock right from the box set idle, set idle mix screws to 1 1/2 turn out and enjoy trust me i've had holeys by the dozen. edlebrocks work wonders in the place of a holley. i have the same horsepower car as you and i went through the same thing.
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1989 firebird formula
Mods: converted from T.B.I. to a carburator 305 to a 350. Flowmater exhaust,hedman shortie hedders,202 heads,350 horse cam,bored.40 over, Edlebrock torker2 intake.
Future mods 400 performer rpm intake (polished) and 600 edlebrock carb, comp roller cam, and way better heads. orpossibly a 383 stroker?
------------------
1989 firebird formula
Mods: converted from T.B.I. to a carburator 305 to a 350. Flowmater exhaust,hedman shortie hedders,202 heads,350 horse cam,bored.40 over, Edlebrock torker2 intake.
Future mods 400 performer rpm intake (polished) and 600 edlebrock carb, comp roller cam, and way better heads. orpossibly a 383 stroker?
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