Dom, is your scoop sealed, if so you wont see a vacumn in the scoop area, specially on top end, that area will be under a slight pressure, about 5"-8" of water at your speed. The loop tube is for a hard leaving car, when you launch the fuel sloshes up and out of the vent falling into the carb causing the carb to go dog rich EDIT also a set up that didnt have a air cleaner and usually no hood, the air passing over the carb would suck fuel out of the vents and spray on the windshield