Engine stalls upon braking
Float adjustment is spot on. Accelerator pump is set right and squirting as it should. I can let it take off on its own, get up to 15 mph or so and hit the brakes with no stalling in forward or reverse. If I hit the gas to take off and then hit the brake it stalls forward or reverse. The two metering screws at the base of the carb are backed out 1-1/2 turns from seated. I don't have a clue as to what's going on with it.
Reduce the pump shot, reduce the idle-timing and increase the idle rpm.
The reduced idle-timing will require an increased butterfly opening to maintain a decent idle speed (minimum 600/650 in gear.
The increased butterfly opening may require a reduced mixture setting, leaning idle back to normal.
The pump shot should be reduced to the minimum amount and timing, to prevent sags in acceleration and hesitations at throttle tip-in. Any more than that is a waste of fuel. To retard the pump-timing,the arm usually has to be installed in a hole further away from the pivot, and re-bent to re-set the stroke length. You can mess with the stroke length, within the limits of the mechanical range of the linkage. Every time you change the idle speed,the stroke length is affected. The factory stroke length is set with the curb idle screw backed right out.To experience what the pump is actually doing, you can disconnect it and go for a little drive somewhere on a deserted parking lot,lol
I have seen this happen in cars with low-stall convertors, and with
too-far closed throttle plates,and with too much pump shot. Under these conditions,the engine does not have enough time to burn off all the pump-shot and then when the butterflies slam shut, engine vacuum pulls in a whopping big pile of fuel, and then you get an instant flooded condition. But not the usual kind of flooded. This is only flooded for the throttle opening. The engine will start right up again, sometimes requiring just a hint of air.
Good luck.
