Q Jet on built Buick 455

[JayZee88]

Hey all,

I got a dilemma with my build. I am swapping another Buick 455 into my 70 Electra. With my new motor I got a stock 455 q jet. It has this cam

http://taperformance.com/proddetail.asp?prod=TA_413-455

also has 9.6 static compression, estimated 580-615 hp, My problem is with the carb requirements. In the Buick community its well known Buicks love alot of CFM. I am looking to rebuild this q jet to handle 900-1000 CFM, but is that even possible? Its going to be a street driven car, and the q jets have good street manners and decent mpg for a 4 barrel.

[Frank400]

Welcome to the forum !

   What is the number on the Quadrajet you plan on using ? 

[JayZee88]

Glad to be here 

the number is 7041540 MF 2320. Its a 800 CFM off a 71 Electra I believe

[carmantx]

That is a good quadrajet to work with and can handle your 455.
It will require idle circuit modifications so it will idle correctly with the cam change.  Cliff can fix you up with the correct jets/rods and other items.

No need to try to increase the cfm of this carb for your engine and driving needs.  It will be sufficient for you.  I run the Buick quadrajet on my Buick 455, with more compression, larger cam and Stage 1 heads.  I race the car some, but mostly street driven.

[JayZee88]

do you know how much work like that would cost? The Q needs a good polishing to 
Just out of curiosity how much CFM cam you get out of one of these Q jets without going crazy on cost?

[carmantx]

I don't have a flow meter to measure.  I am told the Buick carb will flow about 830cfm in stock form.  On mine, I cleaned up the casting marks and opened up the primary side some.  I take out the choke components, and verify the opening of the secondaries.  Both on the base plate and the air valves.

[Cliff Ruggles]

Those carbs actually flow 850cfm without porting or grinding on them anyplace, which I don't recommend anyhow.

Plenty of carburetor for what you are doing.  You will need a superb fuel system to keep it full on hard runs, which is really the deal breaker with big HP.

One also has to consider how little time the engine really spends at high rpm's when you drag race it, or make a hard pull on the street with it.

I use a 1977 Pontiac q-jet on my 455, it's about the same power output as you are building, and it outran a Holley 4781-2 850 DP on the dyno and at the track.  I've also tested it back to back against several other big Holley style carburetors and including a very well set up HP950 and a custom built Holley it still ran quicker at the track with the Q-jet........Cliff

[JayZee88]

im glad to know I won't be starving my 455 of fuel. Is there a electric choke conversion for the Qjet? I am putting headers on and its going on a street/strip 70 Electra.

[carmantx]

The 76-80 Buick quadrajets were hot air choke and 800 cfm.  They can be converted to hot air choke.

[JayZee88]

Is there a electric choke conversion kit for earlier qjets?

[carmantx]

I have heard there is.  Close to $100.  I have not seen or used one.

[Cliff Ruggles]

There is a conversion out there, never tried one.  There are also e-chokes that mount to the intakes for them as well, to replace the divorced choke.....Cliff