Quote:
Originally Posted by Praxiss454
I have two of these rochester model b carbs. The one on the truck has a round shaft accellerator pump. The spare one has a flat shaft.
Is there any reason why one is preferred to the other? I could rebuild either one. I tore the gaskets on the flat shaft carb while disassembling so that one will require a rebuild kit in any case to be useful again.
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This is one persons opinion ... Rochester Bs were tinkered with throughout their existence, 2 changes were pretty major. First, going from the flat to round accelerator pump plunger, which mostly affects which rebuild kit one needs. The second is the position of the vacuum port. In the early '70s, the port was moved from below to above the carb's throttle plate for "better" emissions. With the vacuum port above the plate, vacuum advance to the distributor is cut off at idle because there's no vacuum with the plate closed, making timing at idle a big mess. This can be easily remedied by routing the advance vacuum line into the manifold vacuum and capping the carb's port. Also can't hurt to run a straight edge along where the top and bottom half meet to see if there's major warp at the horn.