I need a help choosing my carburators. Performance upgraded '75 455 motor.

I have a '75 engine upgraded for street performance.
Aluminum heads.
Comp cam w/hydraulic lifters
Dual quad intake
Msd ignition
New oil pump
New fuel pump
Still waiting for double roller chain and aluminum water pump cover and new water pump.*
I want now to choose my carburators. I need 2 carburators for the dual quad, for street performance and drag racing.
Which carburators do you suggest? And how many cfm each one should be? Manual or electric choke is better?

 

2x 500CFM Edelbrocks would be plenty. You only need one with a choke though and I don't know of any made like that. Others will chime in.

 

Holley or Edelbrock are better? So I need one with electric choke and one other with no choke.
Thanks anyway, I was thinking of goingf with 2×700 cfm. But it seems to be very high cfm.

 

I just assumed you had a manifold with Carter, Edelbrock or a Holley base plate pattern or is it made for two QJets?

 

The ones that fit your manifold will be best. You didn't specify which dual quad intake you have, but if it's either the E-brock O65 or one of the Offy single plane intakes, Holley carbs won't fit. Those are designed for AFBs (now E-brock), unless you have one of the very rare dual Qjet Offy intakes. If yours is a tunnel ram then you have more options.

In any case, you'll never use 1000 cfm. Run a progressive linkage. I had the O65 intake on a built 455 with two 500 cfm AFBs and progressive linkage in a 1971 Cutlass. The car got upwards of 14 mpg. I strongly recommend the dual plane O65 over the Offy intakes for street use.

 

I have both, 2 manifolds haven't decided with which to go, waiting to decide about the carbs.

 

Well, I have Offy intakes (one haave spread bores and the other square bores), are they that bad? I have a friend running a fual quad Offy on his 455 buick, and he told me it's working great.

 

"Working great" based on what? His "butt dyno"? The reality is that a well-dialed-in single 4bbl on a correctly selected intake to match your engine, cam, and car will make more HP and turn better times in the quarter. The dual quad is more for looks than performance. I'll personally take a dual plane intake on a street motor. You can get the Offy to run acceptably. Frankly, I'd go with the Qjet intake just for the head-scratching factor at cruise night. That assumes you can dial in two Qjets to work on it, or have access to someone who can.

 

Another carb option on either intake is a pair of 625 cfm Street Demon carbs. They have a similar shape to the AFB but are much better carb. They are based of the Thermoquad with many improvements in a new 3 barrel castings. Spacers may be necessary to clear the back barrels but I would use them anyways due to those intakes low profile. Good luck.

 

http://www.lowrider.com/how-to-tech/...etors/#content

www.dragracermag.com/twin-street-demons-and-lamar-waldens-new-409-a-devilishly-delicious-duo

 

Wow, that phenolic main body seems pretty interesting!

 

No disrespect but your post reads like you have parts but not a plan. You say aluminum heads but not what type or what was done to them. You say Comp Cam but no mention of the specs. Are you locked in to dual quads because you have the intakes & like the look? More details would be helpful.

 

Spring loaded secondaries easily adjusted from the side....