Hy billybobs, some of the four barrel carbs from the fifties used to exibit a stumble at throttle opening, it was because the vacuum in the manifold dropped to near zero, this caused the fuel to stop moving towards the cylinders it deposited itself on the floor and walls of the intake manifold. The "cure" was to increase the size of the accelerator pump, so that some fuel made it to the cylinders. You have already stated that "squirting raw fuel into the carbs on acceleration cures the stumble". so maybe we have confirmed lack of fuel to be the problem, maybe CarbKing will give us some suggestions on how to tune the stumble out of your setup. Does your distributor have vacuum advance? If it does your advance would retard to the static timing point as the vacuum drops to zero, do you think more initial advance would help any?
Last edited by 3B; 07/10/2010 8:52 PM.
