[Eotnak]

Hey everybody, quick question, couldn't find anything useful on google or searching here. I have a locking gas cap on my 70 SS 396 that leaks really bad. I'm looking for a non-locking replacement and I can't figure out if I need a vented, non-vented, or ECS gas cap. fuel tank, from what I can see has 2 lines leading to the engine compartment. One obviously goes to the fuel pump, the other thinner one is connected to a rubber line that someone stuck a bolt into to plug it up.

Anyone know how to tell which cap I need?

 

[Bobby78]

Do you have a charcoal canister? That would be the "vent". Not really a vent but a way to send fumes to the carb and relieve pressure so then a non-vented cap would be what you need. Maybe that's where the hose goes/went?

 

[Eotnak]

My initial thought was that the 2nd line went to a charcoal canister originally. Currently there is no canister, so I figured I'd ask the experts here what is up...

 

[Bobby78]

Yeah I don't really know either. Kinda guessing.

 

[464elky]

If the plugged line is a 1/4" it is a return line which would have connected to the fuel pump. If it is 5/16" or 3/8" it would have gone to a canister. Does it end on the passenger side by the fuel pump?
If it is the 1/4" line you will need a vented cap. If it is either one of the others it would have come with a non-vented cap but you would need to do something to allow the tank to vent. Maybe some pictures would help us help you.

 

[ccc]

464 is correct on this. to use the non vented cap you will need to supply some method of venting the tank. without the vapor canister i would run the vented cap until you can correctly repair your fuel system . if the line went to the fuel pump it was to help ward off vapor lock by bleeding off fuel and vapor bubles back to the tank

 

[gilby]

Hey everybody, quick question, couldn't find anything useful on google or searching here. I have a locking gas cap on my 70 SS 396 that leaks really bad. I'm looking for a non-locking replacement and I can't figure out if I need a vented, non-vented, or ECS gas cap. fuel tank, from what I can see has 2 lines leading to the engine compartment. One obviously goes to the fuel pump, the other thinner one is connected to a rubber line that someone stuck a bolt into to plug it up.

Anyone know how to tell which cap I need?

...yeah,from 1964 thru 1972 are vented gas caps....

http://www.bobschevelleparts.com/1964-1972-chevelle-oem-style-vented-gas-cap.html

:beer:

 

[Eotnak]

yup, the plugged line is 1/4", and the fuel supply line is 5/16". I looked at the assembly manual and saw that there are vented tanks (passenger front side of tank, 2 large vent tubes) and non-vented. I have a non-vented tank. So I'm thinking to go with the vented cap and write myself a note to get the correct fuel pump in the future.

thanks bobby78, 464elky, ccc, and gilby for setting me in the right direction :beer:

gilby, funny thing I noticed. You describe the cap (correctly) as vented, the link says vented, the title of the part says non-vented, description says non-vented, and the picture shows a vented cap. I wonder what I'd get if I ordered it? :smileyb:

 

[ccc]

you are very welcome and good luck:beer:

 

[gilby]

thanks bobby78, 464elky, ccc, and gilby for setting me in the right direction :beer:

gilby, funny thing I noticed. You describe the cap (correctly) as vented, the link says vented, the title of the part says non-vented, description says non-vented, and the picture shows a vented cap. I wonder what I'd get if I ordered it? :smileyb:

...Funny thing,I didn't catch it either..:dontknow:

..if you order it,hope its the correct one..:dontknow:
:beer: