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Projects Gas tank vent, what is that??

Discussion in 'The Hokey Ass Message Board' started by miki562, Apr 21, 2017.

  1. miki562
    Joined: Apr 2, 2014
    Posts: 76

    miki562
    Member

    Hey all! So here I come again with more questions. Well the first gas tank that was unprofessionally installed into my hot rod was this crappy plastic one that is so cheap it's actually warping with the heat
    [​IMG]

    That being said, I think it's time I invest in a decent fuel tank. I found this fuel tank that should work awesomely for my car since I want to be able to use my rumble seat while having a good fuel tank... only question here is... what the heck is a fuel vent??? My crappy gas tank is just a tube with a filler cap and 3/8" hole for the hose.... what purpose does it serve? Do I really need to run that in my bare bones hot rod? Is there a way to cap it off? And is that even safe??

    [​IMG]

    [​IMG]

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  2. the vent lets air in to replace the fuel that goes out...otherwise there would be a vacuum created.make sure to run the vent to the out side of the car

    your old cap probably had a vent hole in it...unsafe!
     
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  3. yes you need a vent. IT allows the vacuum created by the suction of the fuel pump to actually let it suck the fuel out of the tank. with out the vent you will have a hard time getting the fuel up to the fuel pump. I would recommend using a small piece of fuel line, 2-3 inches to attach to a hard line that you will need to bend up to route the vent outside of the body, down under the floor. Put a loop in the hard line to keep from having fuel randomly drip out of the vent from fuel sloshing around in the take and making its way up to the vent port. The most important thing is you want it to vent outside so it doesn't fill the in side of the car with fuel fumes when sitting outside on a hot day.
     
  4. roundvalley
    Joined: Apr 10, 2005
    Posts: 1,682

    roundvalley
    Member

    Google TANKSINC.COM for instructions.
     
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  5. miki562
    Joined: Apr 2, 2014
    Posts: 76

    miki562
    Member

    Man, you guys are always so helpful! Thanks a million, do you happen to have any pictures of this kind of work so that I can copy onto my car?

    That explains why I have to pump my gas pedal so much to have it start!

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  6. miki562
    Joined: Apr 2, 2014
    Posts: 76

    miki562
    Member

    That makes sense why everything smells sp strong in my car... I felt like I was driving a bomb!

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  7. El Caballo
    Joined: Mar 3, 2001
    Posts: 5,842

    El Caballo
    Member

    Get a battery box while you are at it. boom......
     
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  8. miki562
    Joined: Apr 2, 2014
    Posts: 76

    miki562
    Member

    Will do!

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  9. You may still have to pump your gass pedal more that you would think to get it started. I have noticed that the ethanol in the gas we get today seems to evaporate pretty quickly, leaving the carb bowls empty. My 51 Chevy is like that as well as my roadster. let it sit for a few days almost empty carb. Running around town stop for 30 min, bump the key starts right up. todays gas sucks.
     
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  10. Blues4U
    Joined: Oct 1, 2015
    Posts: 1,611

    Blues4U
    Member
    from So Cal

    I've noticed that too, which begs the question, isn't that contributing to smog in the atmosphere? I mean, that gas doesn't just disappear completely, it may be gone from the carburetor, but it's just accumulating in the air above us. I suppose there are so few carbureted cars these days they don't consider it a problem?
     
  11. squirrel
    Joined: Sep 23, 2004
    Posts: 36,641

    squirrel
    ALLIANCE MEMBER

    Starting around 1970 or so, all new cars had evaporative emission controls (charcoal canister). Traps the vapors, recycles them into the engine.

    And I don't think it's the alcohol in the modern fuel, I think it's just that the fuel is more volatile these days.

    yeah, the battery looks scary, stuff rattling around in a trunk can short it out...
     
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  12. woodiewagon46
    Joined: Mar 14, 2013
    Posts: 877

    woodiewagon46
    Member
    from New York

    Make sure the vent you install has a built in check valve to stop the fuel flow in case of a rollover.
     
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  13. theHIGHLANDER
    Joined: Jun 3, 2005
    Posts: 7,005

    theHIGHLANDER
    Member

    This is a proper observation. The charcoal canisters are supposed to filter the hydrocarbons that evap even from injected shi...uh, stuff. It's like waterbourne base coats for automotive refinish. The color, that base coat, it's the lowest volume of product used so we still get VOC from primers, sealers, clear coats. I'm sure the spotted owl, Canadian lynx, limp-dick frogs, and mutant spiders are happy and easily placated. Just sayin...
     
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  14. squirrel
    Joined: Sep 23, 2004
    Posts: 36,641

    squirrel
    ALLIANCE MEMBER

    people gotta breathe, too. My garage sure stinks after I take one of my old ones for a drive!
     
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  15. flatheadpete
    Joined: Oct 29, 2003
    Posts: 8,635

    flatheadpete
    Member
    from Burton, MI

    I love the smell of 'garage'. But I wouldn't wanna live in there.
     
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  16. Johnboy34
    Joined: Jul 12, 2011
    Posts: 805

    Johnboy34
    Member
    from Seattle,Wa

    If there's room you can mount an early style charcoal canister. Run the vent to it, from it to the back of the car, when gas leaves the tank air is sucked through the canister to tank. Gets rid of the fumes.
     
  17. PoRodder
    Joined: Sep 28, 2014
    Posts: 75

    PoRodder
    Member
    from St. Louis

    I believe that a tank vent also allows you to put fuel into the tank without splash back, which can harm some paints. Depends on your filler neck size. A retro charcoal canister would need some type of purge valve, otherwise it could be a vacuum leak.

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  18. BamaMav
    Joined: Jun 19, 2011
    Posts: 1,603

    BamaMav
    Member
    from Berry, AL

    I'm wondering if the plastic tank isn't actually be sucked in by not having a vent instead of the heat warping it. The fuel used has to be replaced by air in the tank, if the fuel pump is sucking hard enough it can collapse a metal tank, much less a plastic one.
     
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  19. Most Caps are vented one way to let air in and not out but the Gas vapors that build up pressure in the tank still need to get out- that's what that vent you're questioning is for. The modern day Evaporative control system (EVAP) handles the EVAPORATE from the fuel with a charcoal canister and some hoses.

    The fill neck should be large and un restricted or have a vent tube inside of it or off the tank into the side of the filler neck.
     
  20. Wanting to keep with the vintage thing and use what I had around, I built a battery box for the 32 from wood. Fresh white pine with a barn door handle on each end. Handles are good to move it and to lash it down. Sides come up above the battery about 1". Cut a couple round holes in the ends and sides. Keep it tied down with a ratchet strap. Works great and looks the part...................
     
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  21. jimmy six
    Joined: Mar 21, 2006
    Posts: 2,020

    jimmy six
    Member

    Where ever you have it vented to add one of those cheap plastic gas filters on the end. No sense sucking in unfiltered air. We use them on all of our race cars. 1/4" minimum.
     
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  22. [​IMG]
    My Tanks installation pic. Line on left goes down through the floor to a filter on the subframe and then forward to the fuel pump and carb. Next is the vent line that goes up, through a gas filter ( per post #21) and exits in the trunk channel where rumble seat latch bolts used to be (see your pic in post #1). My next pic shows the trunk channel, the filter, and the vent pipe exit into the channel. The pic is taken from the opposite direction of your pic in post #1.
    [​IMG]

    The big pipe in my first photo is, of course, the fill. Just behind it, is the overfill drain line that runs down through the floorboard and exits to the side and below the muffler. (Don't want any gas dripping on a hot muffler in the event of a gas tank overfill.)
     
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  23. miki562
    Joined: Apr 2, 2014
    Posts: 76

    miki562
    Member

    T2900XL_lg.jpg

    Thanks for the advice! It was really helpful! So I ended up ordering this little number, it's a modified Model T oval gas tank that's vented, capped and comes with a sending unit! I'm really happy with this purchase

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  24. miki562
    Joined: Apr 2, 2014
    Posts: 76

    miki562
    Member

    That's such an awesome idea!!!! Please share pics! I'd love to see that! I just got this nifty, modified Model T gas tank that I'm thinking about making a cool wood structure for the gas tank and strapping it up with some sweet 3/16" thick leather straps I made!

    [​IMG]



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    Last edited: Apr 22, 2017
  25. 41GASSER
    Joined: Aug 2, 2009
    Posts: 176

    41GASSER
    Member

    As fuel is consumed a low pressure area is created & air comes into the tank. And at times pressure is created and needs to escape. Thats why cars have vented tanks or caps. I recommend a filtered vent to prevent debris from being introduced into fuel system

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    Last edited: Apr 23, 2017
  26. 41GASSER
    Joined: Aug 2, 2009
    Posts: 176

    41GASSER
    Member

    This is my vent attached to a roll over valve and with a filter 20170422_224802.jpg 20170422_224726.jpg
     
    Last edited: Apr 24, 2017
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  27. You have to have a vent bro. Try sucking the coke out of a 20oz bottle without letting air in and you'll see why. A vent replaces the volume of fuel used...with air.

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  28. 5window
    Joined: Jan 29, 2005
    Posts: 5,797

    5window
    Member

    My '31 came with a plastic boat tank that wasn't even bolted down. One trip home (60 miles, was all it ever got. I have been much happier with my Tanks steel tank. You need a vent with rollover protection, as previously stated. That will allow the gas to flow without building up a vacuum and protect against spills, just in case.
     
  29. nugget32
    Joined: Aug 21, 2011
    Posts: 116

    nugget32

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