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Author Topic:   rochester 2bbl
posted April 07, 2003 05:22 PM
whats the cfm on one of these. we got one with 1 11/16" butterflies. gould

You know when you have had a good night dirt racing when you jump in the shower and the tub is muddy brown for the first 10 minutes.

posted April 08, 2003 07:23 AM
The largest cfm rating the Rochester 2bbl's ever had from the factory was 450cfm plus or minus a bit.
Almost ALL the common 2G's you'll find will have that 1.687" (1 11/16") throttle bore size.
There were about 5 different venturi sizes found on them, however, the largest and hardest to find was 1 3/8". That is the only 2G that flowed 450cfm. By far, the most common one found on cars & trucks was either 1 1/4" or 1 5/16".
The 1 3/8" venturi size was found on special applications (grain trucks, C60's, school buses, etc) as well as on the 1971 Pontiac 455ci motor with a 2bbl option.
There are many ID #'s that you'll find will be 1 3/8" venturi. They started out in the mid-60's or thereabouts, and were even used up into the last few years Rochester made 2bbls and were put on marine FORD 4cyl motors (Mercruiser).

There were dozens of booster assembly variations used in the many different 2G applications as well, but that'd take a book to explain....:-)

Hope that helps, and if you'd like more info or help, just hollar.


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