Rochester Quadrajet carburetor 750-800 CFM explained

Rochester Quadrajet carburetor 750-800 CFM explained
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[@davidpotter7484]

Chevy trucks in the 80' had the 800. My 85 c20 is 17080213, i have 6 or 7 of them for spares and parts, same with my 72 c20 chevy 7042208. I have many dealer manuals, tune up books and 1985 gm rochester new product book that lists all the numbers. I have been told, by someone that wrote a book that my gm dealer books are wrong, and that was only made in 78-79. Lol, holy cow. 800 cfm carbs are all over the place on gm trucks still driving around.

[@GlennLittleford]

I picked up a 800cfm model for my mild 350sb. A bit of tuning and modification, and its a perfect carb. No bog or flat spots, great economy, and 400hp on the dyno with perfect AF across the range. I'll never use a Holley again.

[@thisisyourcaptainspeaking2259]

I really like both the quadrajet and the thermoquad.

[@blainesnider147]

Pontiac had 800 on RA4 and SD 455 for sure

[@geezman1000]

I have a milk crate filled with quadrajet carbs. I also have a milk crate full of holleys.

[@vinskeeter]

Thanks for the video. Can the throttle plate bushings be replaced? (If they have them?) My idle is erratic, and I had to install a stronger return spring.

[@radperformanceswepco2372]

Yes you can! you will have to drill out center bore and tap in bushings. Some online sources sell kits for the Rochesters.

[@russellfinkler9092]

(I have a 7043250 ra 1223) qjet every place I look at all these videos and see they are all 750cfm or 800cfm. But called holley today for a replacement holley double pumper and they said a 600cfm is recommended for my olds 455 engine. Don't want to rob my car of hp if it needs. Let me know your thoughts thanks

[@jorgeadolfotrejogarcia2235]

I have a Qjet 750 just like the one you showed. When I increase the throttle gently the engine tries to shut down but if I close the choke plate with my hand the engine stays on. its acceleration. If I accelerate quickly to full throttle it does so but then it tries to shut down, as if it won't suck gasoline.

[@radperformanceswepco2372]

Seems to be a Vacuum leak

[@geezman1000]

I always throw a shop rag over the air horn. If it dies it has no vac leak if it doesn't then it's getting air some other way