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Discussion Starter · #1 ·
so as most of yall know they didn't put a relief vent in the tanks back then.
i'm in the process of figuring out how to make one and also look bad cool.
i just redid my tank and coated the outside with that rubber spray paint stuff.
got my gas cap to set flush with the body. (i was jacked in the past from previous owner)
so now i need a gas tank vent so it wont spit gas out when filling up and also building up to much pressure in the take.
i got some ideas and i want to keep the original gas cap that doesn't have a relief hole/vent in it.
what have yall done and or seen?
 

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Likely because the exterior of the cap is steel and painted body color.

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Discussion Starter · #6 ·
I'll be working on the idea i have for this problem this weekend.
my idea is to get some metal tubing and a canister and tapping into the tank or filler neck to attach the tubing and routing to the canister that will be filled with charcoal with a breather vent.
my canister will prob. look something like this. Capture.JPG I'll have to empty it some how.................
 

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As a suggestion if you do that. Tap into the filler neck as high as possible.
There is less liquid in the filler neck. So less chance of leaking.

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Discussion Starter · #8 ·
so dumb question, it makes no difference where the line ties into? either up high or down low.
 

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Not a dumb question.

Given a choice, the higher the better. As higher will be further away from the liquid fuel.
However you may run into physical restrictions (space) that may not allow for a high up location.

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Discussion Starter · #10 ·
so my idea. rout the line now up high and have the tube coil down into the can. so it looks kind of like this.
49334
 

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Not sure you need the can.

An opening at the top of the filler neck with a fuel hose attached. At the end of the hose is some type of filter to keep out insects. Use fuel resistant parts.

With the can, if any fuel vapor condenses in the can, that is liquid fuel similar to a Molotov Cocktail. If you had a can you would want a vacuum line to suck in any vapor in the can. When that vehicle was originally built any fuel vapor from the tank just vented to the outside.

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Discussion Starter · #12 ·
Not sure you need the can.

An opening at the top of the filler neck with a fuel hose attached. At the end of the hose is some type of filter to keep out insects. Use fuel resistant parts.

With the can, if any fuel vapor condenses in the can, that is liquid fuel similar to a Molotov Cocktail. If you had a can you would want a vacuum line to suck in any vapor in the can. When that vehicle was originally built any fuel vapor from the tank just vented to the outside.

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Didnt think of that...... "Action the man of all great knowledge"
 

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Discussion Starter :
... so as most of yall know they didn't put a relief vent in the tanks back then.

.. admittedly not experienced with1967 Falcons:

Early 60-65 cars all did-do have a fuel tank vent port right by filler entrance, connected to a metal line that snakes up along rear trunk and then out under right side dropoff - under taillight. this 'open-to-atmosphere' fuel tank vent and open carburetor bowl vents were first obvious noxious emission source to be remedied in mid 60's. AFAIK gas caps are not usually vented.

a '71 Maverick tank I have already has the top of tank vent for return to charcoal canister, '67 may have a similar tank vent emissions setup.

Hav efun
 

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a '71 Maverick tank I have already has the top of tank vent for return to charcoal canister, '67 may have a similar tank vent emissions setup.
Interesting you picked 1971
That was the first year of Federally mandated closed fuel systems. Called evaporative emission control.
Except California which adopted the same standard a year earlier.

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Good discussion for the few ...

Now I'm not sure if the spare tank I have is from '71 or '76 'parts' Mavs''. Interested in what OEM venting was used post 1965 before Fed standards?.

have fun

“Do not correct a fool, or he will hate you; correct a wise man, and he will appreciate you.”
 

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Prior to Federal the venting was just to the outside.

There are two things happening and require likely some physics.
1) When filling the tank air HAS to come out of the tank and rather swiftly
2) When closed up with cap on the air has to have a path to come back in when the tank is being drained. In addition the fuel in the tank expands and contracts. So a back and forth air movement has to be possible.

#1 is accomplished with a wide fuel filler neck OR as vent tube from the bottom of the fuel filler neck to the top of the fuel filler neck.

Prior to Fed reg, #2 is accomplished typically with a vented cap. And there is a check valve in the vent to stop liquid from coming out. Especially during a roll over accident. The vehicle above has a painted cap to match the body of the vehicle. Some of these had vented caps as well. Others have a small vent opening in the top of fuel filler neck or some designs will vent in the top of the tank. The issue is the vehicle is over 50 years old. The venting can get corroded or plugged. Usually it is easier to make a mod that no one will see.

Acton
 
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Discussion Starter · #17 ·
TRUE, yet it was stinking hot this weekend and i almost melted to a blob that might have resembled me. So i didnt get any thing done this weekend cuz my shop is my yard.
 

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Like mentioned above, I have a 1962 Falcon wagon and it has an open-to-the-air vent.

If you are installing a vent, it MUST be at the top of the tank, in the air space. Otherwise, you will push fuel up the vent line and out of the tank when the air in the tank expands due to temperature variations. My wife's '73 Buick Century had a vent line running from the tank to a charcoal canister. There was another line that ran from the canister to the air cleaner. The charcoal was supposed to absorb vapors from the tank to keep them from getting out into the atmosphere. The line to the carburetor pulled the collected fumes into the air cleaner and then into the carburetor to be burned. If you want your car to be "pollution free" you might look into installing one of there charcoal canisters. There may be a replacement available for Ford cars that will work for you. As stated above, the vacuum line must be routed such that it goes to a spot higher than the top of the tank to keep liquid fuel from getting into the vent line.
 
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