[jhv48]

The stalling on hard braking can be caused by two different sources. As has been described previously, the rear bowl can be sloshing fuel forward which can cause fuel to slosh up and out of the rear vent and into the main body resulting in momentary flooding of the engine with fuel, thus the stalling. This condition can be cured by lowering the float level, installing "vent whistles", installing road race floats, or buying a 6 inch piece of rubber hose and attaching it to both vent tubes so that if fuel does slosh out of the secondary vent, all it does is go up the tube and into the primary float bowl. If you try this fix, punch a couple of holes at the top of the apex of the hose so there is still a venting function if needed.

The second cause of stalling under hard braking can be from the primary float bowl. When you're hard on the brakes, fuel in the primary bowl flows forward and can cause momentary fuel starvation, as the jets are at the rear of the float bowl and when the fuel sloshes forward, they can be sucking air for a moment. The cure for this is higher fuel level in the bowl, jet extensions, and/or road race floats, or a combination of the above.

Start with the hose connecting the two vents, that will tell you if its the primary bowl sucking air, or the secondary bowl over flowing. Once you know which bowl is causing the problem, and it can be both, you can address each one step by step until the problem is gone.

First, make sure your fuel level is set properly in both bowls before you begin.
Good luck, been there, done that.