Sorry guys, but I can’t buy the bit about the float level. Changing the float level an 1/8" up or down in a Rochester ’B’ carburetor is not going to make a bit of difference in the hesitation of these engines. Whether the truck heading up-hill or down-hill that carburetor was designed to handle a 30° incline without running short on fuel. And if you were accelerating up a 30° incline and you experienced a hesitation because of the float level it would not simply be a stumble but rather a sigh of a dying engine and all the choke in the world is not going to deliver more fuel.
Bill I agree with ya about the octane selector. It was included in the design to compensate for variations in the fuel grade. Back in the day when fuels were not as consistent as they are today, if you got a dose of lower than rated octane fuel you would experience pre-detonation and compensate by retarding the timing. The higher octane fuels with their slower burning flame front would require an advance in the timing to get the power out of them. But once again as you point out, the +/- 5° adjustment would cover all the fuels available for this engine.
I understand the 15° advance in your case. When running a non-stock configuration you can throw the factory specs out the window and you become the design engineer.
p.j. I don’t have the time to study the pump circuit right at this moment. But the only removable jets are the main and power jets. The one common thread in these complaints is that the hesitation usually shows up after the carburetors are rebuilt. Suggesting that the rebuilder did something wrong. But since 99% of the kits are Standard Brands, Hygrade 123A kits could it be possible that the by-pass passage is not the same as the original accelerator pumps? If more fuel is by passed this could result in a lean mixture as the pump is operated. I would love to find an original GM accelerator pump for autopsy. I certainly have a bunch of the after market pumps out of carburetors that have been rebuilt and I would guess that the vast majority of the ’B’s that we run into have been rebuilt at one time or another. I’d be very surprised to find a 60 year old carburetor that had never been rebuilt and was still operating properly.
Denny Graham
Sandwich, IL
