Mechanical secondaries with a variable venturi feature. Good points, straight from Carter and not from a sales brochure.
Venturi: A Venturi is a system for speeding the flow of the fluid, by constricting it in a cone shaped tube. In the restriction the fluid must increase its velocity reducing its pressure and producing a partial vacuum. As the fluid leaves the constriction, its pressure increases back to the ambient or pipe level.
A venturi DOES NOT control the secondary operation. It aids it.
Thank you.
Read the first and second sentence in snipers attachment again. That is what I'm saying. You can't open those secondaries mechanically without some sort of restriction to delay the intake of additional air or you need a secondary accelerator pump shot to prevent a huge backfire and most likely stalling the engine. In other words, vacuum secondary carbs allow the intake of extra air and fuel as the engine demands it, not as a function of the mechanical linkage alone. Block that secondary air valve fully open and then tell us how those mechanical secondaries work.
I don't know why you want to argue this point, it's really useless and unproductive, so whatever, I'm done.
