Gas Cap required

[Gilmore]

I bought new locking gas caps for my 1984 K10 with brand-new tanks and vents. The vents are higher than the tank inlets. However, I am still experiencing puking through the vent onto the ground. I'm guessing my new gas caps are not vented which is causing the puking but I'm wondering if a vented gas cap is required given the vent in the tank?

 

[fast 99]

Came with a charcoal cannister, tank vented there. If that system has been eliminated, tank will need to be vented. Plug vents on tank, install a vented cap.

 

[Gilmore]

Any suggestions on a vented lockable cap? I've been looking on and off for weeks and I can't seem to find anything that will fit the tank neck.