massive reconfiguration time again.

Cope said
Like i said, i dont know if its right or not.

Lets go with the fact that carburetors work on vacuum. We are not talking blow through carbs.
So if my blades are open X amount they want to be drawing X amount of air.
Now if im doing 70 at cruse with the blades mostly shut and a high pressure area above my carbs. Is that high pressure area more than the vacuum of the engine?

What happens then?

you could us that same scenario with sea level air pushing on the butterfly's and not so much pushing on them at altitude.

I think to answer you question. at 70 (ram air) there is more pressure on the top of the carb. pushing more air and fuel into the eng. throttle blade closes slightly to keep the same speed.