Buying New Carb
- Thread starter 76chevyc20454
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rich weyand
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A normally aspirated 454 at 5000 rpm and volumetric efficiency of 1.0 (which you won't get), pumps 656 cfm.
T'were me, I'd get a 750 Qjet.
T'were me, I'd get a 750 Qjet.
firebane
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They are the same the difference is in the venturis on the secondaries. They are slightly larger allowing more air flow.
firebane
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You must be registered for see images
http://www.chevelles.com/showroom/data/500/medium/Q-Jet_venturi_differences.jpg
C10man
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Try to find a used Holley avenger. They make them in 670 and 770 cfm. Has vacuum secondaries but you will need an adapter plate if your truck has an original intake for q-jet
Quadrajet Power
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The primary bores are larger on the 800 cfm quadrajet like posted above. Quadrajets were capable of 750 cfm or 800 depending on that primary casting. Many Quadrajets were limited on the secondary throttle blades to reduce the air flow ability, mostly done for smaller engines with GM.
Many of the 454 truck engines in late 70's early 80's had the 800 cfm body. The better design had the secondary vacuum break mountEd on the front to release the secondary air valves. Some had a rear mount and it is not as desirable design for performance use.
Many of the 454 truck engines in late 70's early 80's had the 800 cfm body. The better design had the secondary vacuum break mountEd on the front to release the secondary air valves. Some had a rear mount and it is not as desirable design for performance use.
firebane
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I apparently have 2 800cfm bodies LOL. I was pulling all my extras apart today and was quite shocked.
