Looking for SU carb explanation.

I'm having some trouble with acceleration under load and think fuel/air delivery may be a problem. Learned the hose was not connected. I assume this creates air pressure in the float bowl? Can someone confirm or correct? What problems would it being disconnected cause?
Also, the pipe is pressure from the engine right? Does this help regulate the air/fuel delivery to the combustion chamber? (Especially when accelerating)

(As a bonus question, how does the Summer/Winter dial factor into this?)

A lot of what I'm seeing on carburetors says the float bowl prefers atmospheric pressure. It seems like the hose would be bad for that, instead matching the pressure coming in the carb's air intake through the airbox. (This is assuming the pipe puts the airbox under positive pressure)

Edited 6 hours ago6 hr by RobotandtheRoad