Previous sentiment was that Avanti gas caps were vented/or not ( didn't make a difference), however it haas been pointed out that the original gas cap on 63-70 Avantis were NON-VENTED.

The tank has a vent/overflow hose running from the top of the tank to the passenger side of the car and will dump fuel over the axle at the leaf spring area.

The vent hose loops up from the top of the tank, closer to the filler side, then along the top of the tank to the right rer sail area. It proceeds up into the passenger side body sail (rear portion of the roof behind the quarter window ) in order to maintain the same level as the filler tube on the drivers side.

FILLING the tank and topping it off will result in a fuel spill over the axle. This would prevent a vented cap from allowing any slosh to exit via the gas cap and run down the side of the body.

The factory likely used a non vented cap to prevent that from occuring. The paint in those days was Lacquer and susceptible to damage by the fuel.

Use the info below at your discretion /


May 2010 sdc #41824 1)Laemmie

I have now found that the proper number for the Avanti is a bit of a pain to utilize..............
Stant number 10623 non locking cap is smooth with no outside serrations and is large to get ones fingers to turn it
........Number 10491 is a locking cap and is smaller so no problem with your fingers...........

but for those who do want a non-locking cap I have found that Stant number 10640 is a direct fit
...and it has raised finger grips.....a breeze to put on and take off.

STANT Part # 10640 OE Equivalent Fuel Cap; 2 17/32" (VENTED) Anti-Surge (1 1/2" x 1 3/8" Shallow Cam)

Category: Fuel Tank Cap

The caps are ALL VENTED anti-surge. I did some detective work with the Stant site and others...........then called Stant directly to make sure.........good to go.........so if you want a non lockable cap go with 10640 or l0491 if you want the lock. ------------------------------------- The 10623 is a pain to remove since it has no serrations to hold onto. --------------------------------------