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11-20-2006, 08:40 PM | #1 |
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Carburetor CFM adjustment
How can you adjust the CFM of a carburetor? Can you adjust the CFM of a carburetor? Is it as easy as changing the size of the jets or is it a little bit more complicated than that. I'm asking because I only need about a 500 CFM for my 307 engine but I like the Holley 4160 carb. So please help me out.
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1968 C-10 longbed, 307 V8, 4spd- currently under construction |
11-20-2006, 08:51 PM | #2 |
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Re: Carburetor CFM adjustment
Not really except on high dollar carbs. On those you can change the venturies
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11-21-2006, 12:06 AM | #3 |
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Re: Carburetor CFM adjustment
Holley 4160 (600cfm) wth vac. secondary will work just fine with the 307. When you floor it the rear barrels will open only as far as the engine can handle.
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11-21-2006, 12:10 AM | #4 |
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Re: Carburetor CFM adjustment
CFM = Cubic Feet per Minute which is how much air will flow thru a carb at a given velocity. As mentioned above, the only way to "change" CFM is to make the air passages/venturi either smaller or larger.
It's kind like asking if you can change a 2 1/2" exhaust pipe into a 3" pipe. Sure, it can be done ... but not by practical means. |
11-21-2006, 12:43 AM | #5 |
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Re: Carburetor CFM adjustment
That's one of the nice things about a vac secondary carb You might need to put in a stiffer spring, but I doubt it.
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11-21-2006, 12:44 AM | #6 |
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Re: Carburetor CFM adjustment
It's actually possible to do this with Weber carbs; kind of a cool feature I don't have any experience with them, but I thought it was possible with the Demon carbs as well - you can just pick up and install another venturi.
Last edited by Billla; 11-21-2006 at 12:59 AM. |
11-21-2006, 12:54 AM | #7 |
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Re: Carburetor CFM adjustment
you could probably bore the barrels and get buterfies to fit. i know it's been done wih throttle bodies not sure about carbs.
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11-21-2006, 01:05 PM | #8 |
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Re: Carburetor CFM adjustment
the big demon carb and holley dominators, $1000 carbs can
you can change the jetting to control the amount of fuel per cubic foot of air but you are going to need to get a smaller carb. you can theoritcialy bore to make them bigger and get butter flyies that fit, but he needs it smaller, you would have to add material to make it smaller. |
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