The Stovebolt Site Forums The Shop Area Engine Shop Can you identifiy this Rochester B?

I've got a really nice rebuilt Rochester b series that I removed from a restored 1960 chevy pick up with a 235. The truck came with another rebuilt Rochester B series carb that was remanufactured by Holley that was never installed on the truck. It runs perfect and seems to be the correct carb for that truck. This mystery carb has 27708 stamped in the horn. It has a 1.750 throttle plate and a manual choke.

Also it had a 72 jet in it which made it run rich on the 235. I swapped in a 53 jet and it ran great on it. This makes me think it was originally ment for a 292.

The bigger jet would have been intended for a smaller-displacement engine, maybe a 216. Less air velocity through the venturi for any specific RPM equals less vacuum, requiring a bigger jet to make an acceptable air:fuel ratio. A Quadrajet for a 305 will run VERY rich on a 350 for the same reason. Float level makes a big difference in overall mixture, also. Higher float=richer mixture.
Jerry

Might be for a 261 they had their own carb.

BTW, it has a larger diameter throttle bore than the one for the 235.

I hadn't thought about the 261.

Does anyone know where i can run down a Rochestere stamping number?

Unless you've got the triangular brass tag with the part number stamped on it, you're sort of SOL. Casting numbers don't mean much on early Rochesters before they started stamping the part number on the float chamber castings. Various carbs with widely different calibrations used the same castings. The bigger throttle bore for the 261 carb makes sense.
Jerry

The larger carb on a 235 will give it more power. I had one on a 55 with split manifold & it felt like you were driving a V-8.

It is my understanding that some B series carbs did not come with a tag, although I also do not find the last four numbers of the part number stamped into the throttle body as I also understand should be there if that was the case with this carb. It sounds like I am SOL. I just hate to let a really good carb to go to waste.. Oh well Thanks anyway.

Why would this carb need to go to waste? If it runs a 235 as great as you say, then use it. Or sell it.

Kurt

Rochesters are pretty tunable, with main jet changes and power valve springs. It might take a while to get the right combination, but I'm sure that carburetor will fit somebody's engine and work well.
Jerry