Cliff's Quadrajet Parts and Rebuild Kits

General Category => Quadrajet Carb Talk and Tips => Topic started by: 70GS455 on April 16, 2024, 12:59:59 PM

Title: 1000+ cfm from a Qjet
Post by: 70GS455 on April 16, 2024, 12:59:59 PM

I ran across this article from David Vizard in his "How to Build Horsepower", Vol. 2. They discuss the mods required to get 1090 CFM out of a Quadrajet.

Title: Re: 1000+ cfm from a Qjet
Post by: 70GS455 on April 17, 2024, 05:26:56 AM

Here is a pic of the first page

Title: Re: 1000+ cfm from a Qjet
Post by: Cliff Ruggles on April 18, 2024, 01:33:14 AM

I haven't seen any of that before but two things for sure.  It is outdated and much of it is not accurate.  Bronze fuel filters weren't used past 1967 for example.  4-6 psi fuel pressure?  The later units will easily work with nearly double that pressure as they moved the hinge pin to provide a LOT more leverage on the fuel inlet needle. 

Thinning throttle shafts and knife edging throttle blades, pretty much a waste of time and the primary shaft is really thin right to start with and delicate enough as-is.

I'll stop there, but most likely that was written quite some time ago and not really detailed enough to provide much help for setting up one of these carburetors for big HP applications......FWIW....

Title: Re: 1000+ cfm from a Qjet
Post by: novadude on April 19, 2024, 12:26:19 PM

I agree that thinning throttle shafts would not be very practical.  Not a lot of material there already... would probably be super fragile if you cut them down more.