CARB SIZE FOR BIG BLOCK
Race Director
Joined: Dec 1999
Posts: 11,096
Likes: 990
From: Sierra Foothills CA
Re: CARB SIZE FOR BIG BLOCK (Pacin'California)
750 cfm for a "mild" motor. Vac sec/ or double pumpers, well, that's a personal decision, I think. :)
-Steve
-Steve
Racer
Joined: Jun 2001
Posts: 289
Likes: 0
From: Duluth GA
Re: CARB SIZE FOR BIG BLOCK (RUDY S)
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.
Racer
Joined: Mar 2001
Posts: 438
Likes: 0
From: Houston, Texas
Re: CARB SIZE FOR BIG BLOCK (zwede)
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.
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.
