OK.... cnay let this go any farther...lol
First... A car has fuel pressure to the carb and the float/needle and seat allow the gas into the float bowl. There is no fuel pressure after the needle and seat in the carb! All automobile carbs have a "accelerator pump" that pumps a small amount of gas when you open the throttle.
Second fuel is not really sucked into the engine by engine vacuume. If that was the case how does a turboed engine with a "blow through carb work? Thats were the boost is pushed through the carb and into the engine... so there is no engine vacuume during boost... yet is still runs? Yes this was a popular way to turbo engine in the past but not seen much anymore.
Fuel actually enters the air stream because of the "Venturi effect" in the carb. The venturi is just a necked down area of the carb either cast in or made by the slide. As air moves through the carb it has to speed up to get through the smaller area causeing the molecules to spread out (less moecules in a area= less pressure or a vacume) the fuel nozzel is placed in the venturi and the atmospheric pressure actually pushes the fuel into the low pressure area.
Another way is to have your discharge nozzel stick into the bore with the engine side of the nozzel cut away... as the air goes over and around the nozzel a low pressure area is created behind the nozzel and again fuel enter the low pressure area.
Thus a pressured carb (turbo) has the float bowl pressurized and the ventury makes a lower pressure area than the foat bowl and the fuel enters the carb.