Last weekend I came across a situation where I believed my fuel cap was leaking. I replaced the old vented gas cap with another vented one. In GU, they list a vented and non vented cap for 64-67. Does anyone know what application would get a vented and what would get a non vented one? Any downside of runnning a non vented one?

Last weekend I came across a situation where I believed my fuel cap was leaking. I replaced the old vented gas cap with another vented one. In GU, they list a vented and non vented cap for 64-67. Does anyone know what application would get a vented and what would get a non vented one? Any downside of runnning a non vented one?

El Camino and wagon use a vented cap, and the other Chevelles use a non-vented cap.
Bruce

ditto

Doesn't it depend on whether you have a return line from the fuel pump to the tank. If so then unvented. I have no return line on my Z, and it's a vented cap.

I have no return line, which makes sense that its vented. Do all wagons and el caminos have return lines?

I have no return line, which makes sense that its vented. Do all wagons and el caminos have return lines?

64 to 67 El Caminos and Chevelles do not have return lines, as original.

64 to 67 El Caminos and wagons have a high filler location on the side and a vent from the tank to the filler tube that requires a vented cap.

64 to 67 Chevelles, other than El Camino and wagon, have a low filler location at the rear and the front of the tank is vented, so they use a non-vented cap to keep gas from spilling under acceleration.

Bruce

And of course around mid-1970 the evaporative emission control system hit and they all went to non-vented gas caps.

You gotta love El Caminos on right handed corners though... smell city! Just think you could run a vented cap on your Chevelle and smell every time you stepped on it or pulled away from a stop.

That's kind of how I found the faulty cap. I was testing the cars ability to draw black circles in my culdesac. It does a very nice job! It also spewed gas out the rear like a garden hose!

ROFLMAO -- extra credit for doing your signature in rubber B)

After awhile that gas out there will help things spin around too!

That's kind of how I found the faulty cap. I was testing the cars ability to draw black circles in my culdesac. It does a very nice job! It also spewed gas out the rear like a garden hose!
You should have gotten pictures...Nothing like a good donut or two!!! :)

Thanks! It was fun now that it doesn't hop like a rabbit - No help needed with my motor and tire combo - I can spin em at will, no revving or clutch work required.