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Thread: Carburator CFM
          
   
   

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  1. #1
    Hopper111 is offline CHR Member Visit my Photo Gallery
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    Carburator CFM

     



    Can someone tell me how to choose how much carb. i need to look to buy for my engine? I'm under the impression that there is a formula to figure CFM...

  2. #2
    Ives Bradley's Avatar
    Ives Bradley is offline CHR Member Visit my Photo Gallery
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    Well according to my info, take the engine size say 460XMax rpm say5000XVolumetric efficiency divided by 3456= CFM. So460X5000=2300000X.85[most rebuilt engines have about 85% efficiency]=1955000 dividedby 3456=565.68287, or less than 600 CFM. This is only a place to start for some, but it has worked real well for me like it is.
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  3. #3
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    I like Denny's formula....cubic inches times 2.
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    From Offenhauser.
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    IMHO, the Offy 360 is one of the best manifolds you can run on a SBC. I ran one on a basically stock 400 SBC in a '62 pickup. The only changes were an earlier double roller timing chain, an old Isky 30/30 cam, a 650 Holley DP and Hedman headers. It made good low end power and peter out until around 6 grand.
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  6. #6
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    Originally posted by Ives Bradley
    Well according to my info, take the engine size say 460XMax rpm say5000XVolumetric efficiency divided by 3456= CFM. So460X5000=2300000X.85[most rebuilt engines have about 85% efficiency]=1955000 dividedby 3456=565.68287, or less than 600 CFM. This is only a place to start for some, but it has worked real well for me like it is.
    You just made my head hurt.

    Originally posted by techinspector1
    I like Denny's formula....cubic inches times 2.
    That's what I'm talking about...
    Wes...aka "BigRed"

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