I still do feel they are drowning the engine when you mash it.
Nope- - - -you're going lean, not rich. Opening up too much venturi area slows down the air velocity so much the vacuum in the venturi drops, and it can't develop enough vacuum to draw sufficient fuel into the airstream. Instead of messing around with the rate of opening, restrict the opening of the secondary barrels to about 1/2-2/3 of their total travel. That will moderate the flat spot somewhat by preventing the throttle plates from opening fully. If you could rig a HEAVY return spring to come into play at that point then it would make you think about giving it any more gas until the RPM comes up. It's not a substitute for over-carbureting the engine, but it sort of keeps you from giving the engine more throttle opening than it needs. The spring-loaded air valve on a Quadrajet is a good example of an idiot-proof carburetor. No matter how far the throttle plates are opened, the air valve only allows the right amount of air to enter the secondary barrels.
Jerry
