RUDY S

I BUILDING A 454 FOR MY 69 VETTE,4 SPEED WITH A MILD CAM. WHAT SIZE OF CARB WOULD WORK??? :crazy: :crazy: VAC SEC OR DP??? :seeya

Shark Racer

750 cfm for a "mild" motor. Vac sec/ or double pumpers, well, that's a personal decision, I think. :)
-Steve

Les

I agree w/ Steve...with more mods I'd recommend an 850. There's been some very lively debate over preference of vacuum vs. double pumpers- you may be able to find info by searching archives here. You'll get better milage w/ vacuum if that counts for anything.

Pat 69BigBlock

Can you give me some of the details on the engine that you're building? My matching numbers 427 has lost alot of its performance and I'm thinking of storing it and putting in a crate motor or possibly building a 454.

oger

There is no better carb for a mild street motor than a Qjet.

zwede

750 is plenty big for a big-block. I made 490 hp with a cheap 750 VS.

noskillz

Don't over carb. So many people like to recommend huge carbs for street. I have seen recs for 950 Demon carbs on this forum before! :rolleyes:

Someone posted a formula you can use. I think it is on the Holley site as well. This formula uses displacement, rpm, and volumetric efficiency to determine carb size. When I ran my 427 through with 80% effeciency, it came back with 700cfm and 80% is probably optimistic at that.

Right now I am running a 600cfm Holley double-pumper on my 427 and it works great. No loss of power at upper rpm at all. The response (metering signal) is awsome.