Perhaps you could turn the carb around so the light shines on the side you're taking a photo of...so we could see the throttle linkage better? The idle mixture screws are not tamper proof, and they're easily changed...so I wouldn't base an ID on that.
The linkage arm looks Chevy...but they mostly had the fuel inlet on the side, and used the larger fitting with a filter inside. Neat mystery. Someone knows, but not me.
I think 56-58 265/283 might be it. Perhaps they started using the side fuel inlet around 1959? The bowl vent fitting is another clue...
I think they started the side inlet in 65. My Rochester manual only goes up to 1962 but still shows the front inlet
If you are looking for a rebuild kit, if you can find one, they are now mostly generic, not assembled for a specific carb number.
https://www.southeastchevyparts.com...ochester-2gc-carburetor--remanufactured_p_242 https://www.southeastchevyparts.com...rochester-2gc-carburetor-remanufactured_p_229 I think they are pretty accurate...I recall my 61 having a side inlet, it was pretty much all original still in the 1970s.
Rochester used the roll-stamped numbers on the float bowls beginning some time in 1968, so that puts yours before that time. As to the fuel inlet location…. As I’ve understood it, the fuel inlet was changed from front to side after 1958, but @Moriarity showed us a manual that shows otherwise. I have a tuning manual published in 1957 showing a front inlet, and I found one for ‘61-65 showing a side inlet (https://carburetor.ca/manuals/cm011.html). I’m not sure what to make of all that. This is a good question for @carbking. edit: just saw the previous two posts! John
Heck, maybe my manual was using some generic pictures.... I do know the 58 carbs on my Man a fre are front inlet
A little: (1) The Rochester Master Parts book has generic pictures. Go by the part number, and look up the part. (2) The throttle arm on the subject carburetor is Chevrolet. (3) Front inlets were used ON SOME MODELS as late as 1965. (4) As previously mentioned, roll stamps began in 1968 (a function of smog emissions). (5) Idle vent valves (the funky stamped steel arm and rubber valve) began on Chevrolet in 1958. Since this carb does not have the idle vent valve, GUESSING 1955~1957. EDIT: Rochester produced 3,466 DIFFERENT models of carburetor from 1949~1979. Close to half of these are 2 barrel. Making a specific statement that applies to all can often miss one (or more). Like those words "first", "last", "always", "never" that generally should be avoided. Jon
I have been racking my brain trying to remember where the carb came from. A guy once gave me a box of parts after he did an LS swap. It sounds like the closest possibility. Does a 57 Nomad make sense?
Definitely a Chevy linkage arm, no external bowl vent lever (started in 58) so I would say 1957 Nomad would be likely. However, Nomads being a high-end car at the time, I would be surprised to see one with a 2 bbl. No matter, it’s most likely a ‘57 Chevy carb. Good carb.
Narrowing it down a bit further, the '55 carburetors didn't have the large hole in the throttle arm for a rubber bushing, so '56 at the earliest. Also, 1963 is the last year Chevrolet used the choke housing on the side of the air horn. Starting in '64, the two barrels used a divorced choke on the intake manifold.
The idle vent valve may be thought of as a part of the hot idle compensation circuit. In very hot conditions, the fuel in the bowl expands, even percolates, especially at idle (and even more true with the p/p for fuel our benevolent government thinks we need). The expansion creates pressure greater than the normal atmospheric pressure in the bowl, thus causing the balance of negative pressure in the idle wells, and atmospheric pressure in the bowl to be disrupted. This causes more fuel to be placed in the idle circuit. In short, the idle vent valve helps to prevent the engine running too rich, possibly stalling, due to additional pressure in the bowl. This feature is also aided, at least on SOME Rochester carburetors, by the slotted throttle body to bowl gaskets. While the idle vent valve relieves pressure in the bowl, the slotted gaskets relieve pressure above the thottle plates. Jon
Carburetors were miraculous mechanical devices which could compensate for changing conditions without a wire in sight. Amazing instruments in their prime and still today.
Thank you. Here’s why I asked. Early unit had a very small vent at the air horn so ok it makes sense. But later unit received a much larger vent with tube at the air horn but still have the idle air valve.
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