4 barrel cfm

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September 28th, 2015, 01:56 PM

Bobby455

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Location: East Hartford, CT

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4 barrel cfm

I have a 71 350 with a 4 barrel, stock, came with the car, never been changed. I'm wondering if anyone knows what the cfm rating for this carburetor is? I looked it up and one article said 750 cfm but I really don't think that's right

September 28th, 2015, 04:11 PM

Fun71

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Location: Phoenix, AZ

Posts: 13,782

Yes, that is right. QuadraJets are vacuum secondary carburetors so they flow only what the engine demands, up to their maximum flow capability, which in this case is 750 cfm.

September 28th, 2015, 06:23 PM

MDchanic

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Location: The Hudson Valley

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Quote:

Originally Posted by Bobby455

... one article said 750 cfm but I really don't think that's right

Why not?

- Eric

September 29th, 2015, 05:38 AM

joe_padavano

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Join Date: Mar 2007

Location: Northern VA

Posts: 47,343

Quote:

Originally Posted by Bobby455

Keep in mind that the secondary air valves on the Qjet only open as needed in response to mass airflow needs. The carb "self regulates" it's CFM rating to match the needs of the engine. On smaller motors (like the 307s), the secondary air valves are actually restricted by a stop so they only open about 70 degrees instead of the full 90 degrees.