How much cfm is a 72 454 original rochester quadrajet 4 barrel carb have? Thanks Eric
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Re: 72 HOW MUCH CFM STOCK ROCHESTER
Eric-----
I can't tell you the EXACT CFM rating of the carb, but I can tell you that virtually all 68-72 Rochester Q-Jets were in the 750-850 CFM range.In Appreciation of John Hinckley -
Re: 72 HOW MUCH CFM STOCK ROCHESTER
There are two basic Quadrajet models. One flows about 750 CFM and the other is about 800. Both of these flow rates are at the industry standard 1.5" Hg. depression used for four-barrel carburetors. I believe the difference in flow is due to two different primary throttle bore/venturi designs, and large engines usually use the 800 CFM version.
Because of the Quadrajets generous flow, there's no reason to replace a Quadrajet with a hot rod carburetor in order to increase flow. The Quadrajet has some limitations, but air flow is not one of them.
The Quadrajets design was inspired by emission considerations. The small primary bores/venturis generate a good metering signal during normal driving conditions, which is necessary for good emissions performance, and the large constant velocity secondaries have plenty of air flow for WOT operation, where emissions are not an issue.
DukeComment
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Re: 72 HOW MUCH CFM STOCK ROCHESTER
The Q-jet would be in the area of 750cfm for the small block. The only car I know of that had bigger than 800cfm was the 71 Buick Riviera GS with an 850 cfm. I don't think even the big block Vettes/Chevies had one this big....
Hope that helps....Comment
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Re: 72 HOW MUCH CFM STOCK ROCHESTER
My Rochester book gives these figures:
1-3/32" primary venturi = 750 CFM
1-7/32" primary venturi = 800 CFM
Apparently the secondaries were the same for both variants.Comment
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Re: 72 HOW MUCH CFM STOCK ROCHESTER
Good info Bill, I can't imagine them putting a 800cfm on a small block. I know the Riviera GS had a big Quad on it 'cause I owned one for years.Comment
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