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  • Fuel tank venting

    What do you guys use for fuel tank venting? This isn't a fuel cell application, stock tank supporting EFI, I used to just have the factory deal, but discovered that the tiny hole in the factory fitting on top of the tank could cause a vacuum situation at low fuel levels and high consumption/ low return rate situations, meaning WOT. I rigged up a larger line on the '71 convertible a couple years ago but I occasionally smell gas. It vents under the car above the rear end housing. I saw the II Much Fabrication deal in Violent Valiant build here on Bang Shift and I think it looks promising. What works for you guys?
    Drag Week 2006 & 2012 - Winner Street Race Big Block Naturally Aspirated - R/U 2007 Broke DW '05 and Drag Weekend '15 Coincidence?

  • #2
    Bill, I ran into that. I just took a drill bit and drilled a couple of holes in the inside of the gas cap to make it vented. Never had the problem again.
    Life is short. Be a do'er and not a shoulda done'er.
    1969 Galaxie 500 https://bangshift.com/forum/forum/ba...ild-it-s-alive
    1998 Mustang GT https://bangshift.com/forum/forum/ba...60-and-a-turbo
    1983 Mustang GT 545/552/302/Turbo302/552 http://www.bangshift.com/forum/forum...485-bbr-s-83gt
    1973 F-250 BBF Turbo Truck http://www.bangshift.com/forum/forum...uck-conversion
    1986 Ford Ranger EFI 545/C6 https://bangshift.com/forum/forum/ba...tooth-and-nail

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    • #3
      I remember a rule about vented gas caps. As in, NHRA doesn't allow them.
      My fabulous web page

      "If it don't go, chrome it!" --Stroker McGurk

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      • #4
        I also drilled a hole through my stock fox body gas cap. It never leaks a drop out of it even when tank is full.
        78 se trans am,67 rs ss camaro,69 BBO Javelin,55 chevy and a bunch of other junk that needs finished.

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        • #5
          I have a stock tank with a sump welded in the bottom, Draw is from the sump of course, return is threw the stock draw enlarged to 1/2", vent is the stock return. I ran a line up to a rollover check valve through the floor of the trunk and ran a hose back down from the check valve through the trunk back down above the axle as to keep the vent outside the trunk.
          First place SSBBNA 2014 and 2015
          Second place SSBBNA 2016
          Third place SSBBNA 2017
          Quickest ET in DD and Quickest Pontiac 2008, 2016 and 2017
          All 13 years of Drag Week in a Black 1969 Pontiac with Pontiac Power

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          • #6
            Mine is a regular locking Stant cap. A small hole just through the first layer is all I needed.
            Attached Files
            Life is short. Be a do'er and not a shoulda done'er.
            1969 Galaxie 500 https://bangshift.com/forum/forum/ba...ild-it-s-alive
            1998 Mustang GT https://bangshift.com/forum/forum/ba...60-and-a-turbo
            1983 Mustang GT 545/552/302/Turbo302/552 http://www.bangshift.com/forum/forum...485-bbr-s-83gt
            1973 F-250 BBF Turbo Truck http://www.bangshift.com/forum/forum...uck-conversion
            1986 Ford Ranger EFI 545/C6 https://bangshift.com/forum/forum/ba...tooth-and-nail

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            • #7
              Originally posted by CDMBill View Post
              What do you guys use for fuel tank venting? This isn't a fuel cell application, stock tank supporting EFI, I used to just have the factory deal, but discovered that the tiny hole in the factory fitting on top of the tank could cause a vacuum situation at low fuel levels and high consumption/ low return rate situations, meaning WOT. I rigged up a larger line on the '71 convertible a couple years ago but I occasionally smell gas. It vents under the car above the rear end housing. I saw the II Much Fabrication deal in Violent Valiant build here on Bang Shift and I think it looks promising. What works for you guys?
              Depending on what year the car is .. but now days(since back in the 70s) we use a pressure/vac
              cap and a small amount of vac or pressure in the tank is common... if you dont like the smell issue
              that can be corrected with a charcoal canister attached to the vent line... if you believe that you
              are getting too much vac at WOT then yes you need a larger vent line .. either another line or a
              completely new line(larger)

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              • #8
                I did the larger -8 line on the 71 and created the fumes issue. I have gone ahead and ordered the II Much Fabrication unit in a side mount configuration. I'll add pictures when it arrives. Or check out their link on the BS Sponsors page. I like to support the companies that support us whenever possible. Spend some time on their site and check out the tech blogs and stories. I learned a ton.
                Drag Week 2006 & 2012 - Winner Street Race Big Block Naturally Aspirated - R/U 2007 Broke DW '05 and Drag Weekend '15 Coincidence?

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                • #9
                  I made my own charcoal canister out of a Summit take apart
                  fuel filter... the one with just the screen in it... its large enough
                  that I poured the charcoal from a junkyard canister into the filter
                  but I added another screen so the charcoal stays in it... I have
                  to take it off once in a while to purge the vapors(just hook up a
                  air hose to the end with low flow for overnight).. that takes care
                  of the fumes

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                  • #10
                    Clever approach. This is the II Much Fabrication unit. It is not a Charcoal absorption unit, it is a vapor/liquid separator so it requires no maintenance. They have been tested by Aeromotive up to 1400 HP and are recomended by Aeromotive among other fuel system and tank makers. In my case it will mount to the trunk lid hinge spring bracket up and out of the way so the trunk can be packed for Drag Week etc. The pictures are all theirs as you can tell; I'll post mine when I have the unit set up. It will be venting an Aeromotive stock style tank with the Eliminator in tank pump. I'll be adding a roll over check valve in the tank to vent unit line to meet NHRA requirements. The cap will remain non-vented as factory.

                    The install pictures are on a '69 Camaro which is way more sano than my shabby heap. Lines and fittings are up to the car builders preference.


                    The bracket shown here is owner fabbed, i will bolt mine directly to the trunk hinge bracket and save the weight.


                    Drag Week 2006 & 2012 - Winner Street Race Big Block Naturally Aspirated - R/U 2007 Broke DW '05 and Drag Weekend '15 Coincidence?

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                    • #11
                      Looks Heavy,,,,,,,, Just Sayin
                      2007 SBN/A Drag Week Winner & First only SBN/A Car in the 9's Till 2012
                      First to run in the .90s .80s and .70's in SBN/A
                      2012 SSBN/A Drag Week Winner First in the 9.60's/ 9.67 @ 139 1.42 60'
                      2013 SSBN/A Drag Week, Lets quit sand bagging, and let it rip!

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