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Author Topic:   Rochester 2bbl carburetor ID and modification
Dirt Roller

Total posts: 8
posted January 31, 2003 08:55 PM
I have two rochester 2bbl's with 1 3/8 in venturies. From what I have found on the intrenet, the math works out that these are 614 CFM carbs. Does this sound right to anyone? Also does anybody have any quick and easy modifications to help the carb perform better and instruction on how to do the modifications? Keep in mind that the carb must appear to be unaltered.


redneck bubbas racing
Dirt Freak

Total posts: 213
posted February 01, 2003 12:10 AM
Sorry to have to tell ya but theres no way they are 614. More than likely 425-450 cfm. Kinetic performance should be along shortly to help you out.

Dirt Full Roller

Total posts: 32
posted February 01, 2003 09:31 AM
Redneck might be right as far as actual air flow, but it is the big 2g. As far as modifying one, there is a really good artical in the July 1995 issue of Stock Car Racing magazine if you want to do it yourself. The Carburator Shop in Ontario CA. can sell you a stock appearing one that flows 625 CFM, but your going to pay big for it. Look at "SLEEPY YOU STILL OUT THERE", one of the guys from SCR left his e-mail address. He may be able to help get a back issue. Better yet get him to reprint it - I can't find mine.
The phone number for the Carburator Shop is (909) 947 7744/9722 if they're still in business. I haven't had any conact with them since 1996.

[This message has been edited by STREET16 (edited February 01, 2003).]

Dirt Freak

Total posts: 408
posted February 01, 2003 10:15 AM
I don't believe that the "carburetor shop" in CA is still in business. There is another business with that name in the midwest but it is not the one everyone speaks about when the subject of modifying 2G's comes up. They deal more in antique carbs and parts.
As for cfm ratings of the 2G's, the largest 2G ever made was a 1 3/8" venturi, and 1.687" throttle bore. Those carbs were rated at no more than 450cfm, and honestly, Rochester's own rating was 435cfm, so to even say 450 or 500cfm is pushing the limit of reality.
The only way to get over 500cfm is to modify the booster assembly, venturi diameter and/or throttle bore and shaft. Anyone who claims a carb flows more than 500cfm with a 1 3/8" venturi and 1.687" butterflies is inflating their numbers or just bragging.
And any 2G that honestly flows over 600cfm won't be able to pass any tech inspection out there.

If there's anything we can help with as far as modifications go, feel free to ask. We build them all the time from mild to completely insane and have many parts and cores in stock. We also can supply rebuild parts cheap.

Dayton Umholtz, owner
Kinetic Performance

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