One more bit of carburetor trivia- - - - -having an airflow-related volume control valve in the secondaries is really nothing new. At least some (maybe all) of the Rochester 4G square footprint 4 barrels in the 1950s used spring loaded air valves in the secondary bores. Those carbs also had two floats- - - -one each for primary and secondary circuits, similar to how Holley 4 barrel carbs work. The 4G had a tiny float chamber volume- - - -under full throttle operation it was possible for a slightly low float level to cause the float bowl to run dry and cause a nasty lean surge. I believe some of the Carter AFB series had a weighted air valve that served a similar purpose.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!