I just installed my professionally rebuilt Rochester single barrel carb from 1949 Chevy 1/2 ton truck with 216 engine. Tune-up went well - timing, dwell angle, idle speed, vacuum, fuel mix.... The engine sounds great. Unfortunately, I'm having one problem. When accelerating or under light load, the engine stumbles, sort of like its not getting enough gas. Is there an adjustment on the carb - perhaps with the accelerator pump, that can be checked or adjusted? Prior to having the carb rebuilt there was no hesitation when under load. With the engine tuned so well, I'm sort of at a loss. Having only rebuilt the carb, it seems like this must be a carb issue. Any ideas what I might look for?