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Author Topic:   2-barrel carbs
Dirt Newbie

Total posts: 3
posted June 11, 2001 10:09 PM
does any body know what would be the biggest 2-barrel carb for a chevy,has to be an OEM part to be legal,thanks

Dirt Maniac

Total posts: 165
posted June 12, 2001 12:31 AM UIN: 54865418
the one you are looking for came on school buses witha 350 they have a goveren on them that you have to take off and put a regular base on them they are getting hard to find the next best is on c-60 dump trucks

Dirt Full Roller

Total posts: 57
posted June 12, 2001 07:36 AM
The largest venturi size made by Rochester Engineering for ANY carb, no matter what it was used on is the 1 3/8" diameter body. Whether it was used on the old '60's school buses or large trucks, the venturi diameter was never made larger than that. There were, tho, other differences between those carbs that had to do with things like power valve sizes and ratings, needle and seat sizes and accelerator pump linkage differences and geometry, among other not-so-easy-to-measure things. All 2G accelerator pumps are of the same diameter, which is larger than the quadrajet pump capacity (fwiw)....but I digress...the large bore Rochester 2bbl could also be found on '71 Pontiac 455's, besides those applications listed above in another post.
Also, the largest baseplate Rochester used was the 1.6875" throttle bore size and they were used on almost all of the later model 2G's with their main differences being in the throttle linkage design and the addition or deletion of various vacuum ports and/or PCV ports.
Let us know if you need additional info or are looking for a carb, we can set you up with no problems.
You can reach me here by replying, or PM me, or email me directly at, or (day job)....or feel free to check the website (see banner above) and contact us thru there by phone.

Hope that helps,

Dirt Full Roller

Total posts: 66
posted June 12, 2001 03:09 PM
I don't know about your class but my bomber class can run ford 2bls. I have found excellent carbs on ford 400 truck engines. At certain tracks we can run with the whole top of a ford 2bl (choke and all) cut off and polished for maximum air flow.
I don't know if this will help you but thought I'd let you know.

Dirt Newbie

Total posts: 3
posted June 20, 2001 09:55 PM
thanks a bunch guys, gonna go hont throught a big truck junk yard they have lots of old buses and stuff of that sort, thanks a bunch,


Dirt Roller

Total posts: 19
posted June 21, 2001 10:46 AM
Something I found really helpful when hunting for the BIG 2GC (factory rated 435 cfm?)was a measuring tool I made that dropped into the carb. The difference between the big one and the next biggest (417 cfm?) is so subtle that without a tool you will be forever thinking you found THE ONE (when I did finally find one after checking 200 or so carbs it did have the governer baseplate but I understand that many don't).
My tool (which looked like a "U" at the measuring end)was just a 1 1/2" x 6" piece of sheet metal with a square cut out of one end that I sized so that when dropped in from the top(past the choke) it would fit over the part of the carb between the large venturies on the largest carb only (the space between the 2 venturies is SMALLEST on the BIG carb)
good luck

BUT IF YOU WANT TO WIN (and your carb is not subject to a claim) I'd just buy one already set up for racing from Kinetic or speedway .......

Dirt Forum Racer

Total posts: 93
posted June 21, 2001 12:36 PM
There might be another avenue here, I'm not for sure, but I had great success with the rochester dual jet off a 1979 heavy truck with 350, of course that was a long time ago when I was racing a Modified Buick V6. I wonder how this carb compares to the Holley.

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