vented or non vented gas caps

[dougs68ss]

im stumped on which cap to use, im switching to a aero style and dont understand the diff. car is carbed with mech pump and stock tank.... thanks

[gbeck1]

Vented! like the original or you may suck the gas tank in (Like colapsing a coke bottle by sucking the air out of it.)
I put a non-vented cap on my 69 camaro and after 3 hours on the intersate it sucked the bottom of the tank up and lifted the fuel pickup tube out of the fuel level. I hated leaving it on side of the road to make the 4 mile walk to the next exit for gas.
:drive1:

[Chad-1stGen]

All depends on your tank. Some aftermarket tanks like Rockvalley have the ability fit a vent line to the tank. My 68 camaro stock tank vented through the cap so a vented cap was needed.