super six carb ?

i picked up my super six setup from a junkyard last week. its a carter carb. after i got hom i realized when i was pulling hoses off, one hose nipple must have pulled right out. its a big one, probably 3/8 but i dont think its pvc. i believe its toward the front, upper passenger side. what is th eupper section of this car ther eis a sheet metal dust cover on the top, i removed the screw puleld th ecover off and it almost looks like the hose nipple is just for a vent? it doesnt look like a vaccum source, am i wrong? do i need it?