All Carters are mechanical in there operation, but the air door above it make it operate like a VS carb. The AVS and TQ have spring loaded doors that can be tightened up or loosened.
The bigger TQ can be used with ease and is not to big because the spring loaded secondary door opens apon engine demand, slowly opening so the engine dosen't bog. And if it does bog, tighten up the doors spring.
Generally speaking, there considered a 800 or 850 cfm's.
Thermoquads.com , Demonsizzlers site of carbs and TQ's.