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Discussion Starter #1
I'v work on a ton of carbs in the past and feel I know a good deal about them. However, I have a question that perplexes me. What difference is there between a 600cfm 2bbl carb and a 600cfm 4bbl carb other than the obvious. They both flow 600cfm right? This question also applies in other cfm's.
 

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In theory they will both flow 600 cfm if installed on the same setup. In the real world engine sizes, manifolds, cams and etc all dictate what a carb will flow. For example if you stick a 850 on a stock 302, dont expect it to flow 850cfm. The differance between a 2bbl and a 4bbl of the same cfm rating is obvious, the differance in the size of the throttle plates. The 600 2bbl is better suited for racing where full throttle is used most of the time where the 600 4bbls small front throttle plates are much better at slower speeds and part throttle operations. I used to run in a stock car division for several years that only allowed stock unmodified 4412 500cfm 2bbls. They are great in that situation but I remember one winter when I needed my truck really bad for snow plowing and the stock carb gave out and I had to borrow the 4412 for my fe 360. I jetted it down and it got me by till I could get a needle and seat for my stock carb but let me tell you about the gas it used. I needed a tanker truck to follow me around. mm
 

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Discussion Starter #3
carbs

I get it? Thanks.
 

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Re: carbs

Not only that you get better gas milage. With the 600 cfm 2-barrel your always flowing 600 cfm. But with the 600 cfm 4-barrel the two in the front flow 300 cfm and the two in the back flow 300 cfm. So if you don't get on it, and drive it easy you only run on the two front barrels (300 cfm), and when you do get on then the rear two will kick and you will have 600 cfm.

~Joe~
 
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