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Technical Aluminum Fuel tank questions

Discussion in 'The Hokey Ass Message Board' started by kscarguy, Mar 26, 2014.

  1. kscarguy
    Joined: Aug 22, 2007
    Posts: 1,571


    I want to modify my dual aluminum fuel tank(s) on my cabover to allow me to run in-tank fuel pumps for Throttle body Fuel Injection on my 406 SBC.

    I have some Questions.

    1. Is there an inexpensive way to mount pumps into the tanks?
    2. Who supplies various flanges that I can weld onto the tank and use to mount the pumps?
    3. How do I isolate the tank from the steel mounting surface?
    4. Can I drill and tap the 1/8" aluminum so that it will hold a bolt on flange? (is it thick enough)
    5. Does anyone sell a weld in flange to use factory GM style pump pickups with the twist ring?
    6. How big should the internal tray be...and how big for the drain/fill hole on the end?

    Any other advice anyone can offer? Thanks in advance.
  2. hayu
    Joined: Feb 8, 2010
    Posts: 30


    "Tanks" has everything you need.
  3. stimpy
    Joined: Apr 16, 2006
    Posts: 3,547


    need to know the shape and how your going to attach it ( side saddle , in frame rail , off frame rail , underslung )

    1st thing , the fuel tank should be 3/16ths minimum for aluminum specailly if its outside the frame rail

    as for pumps you can put a factory style pump in there off a bracket , the best design I have seen to date is a 4th Gen F body as it has a catch cup for the fuel to keep the pump covered at all times .( running the pump dry for a few seconds is the killer on these as it cools and lubes the pump )

    for a acess , no gm tank is aluminum they are steel or polys ,
    if you want copy the aircraft style ring and adapt it to hold the GM style pump assy in place the inner tank ring is 2 peice or weld it in place as a doubler to bolt the top ring too

    as for mounting a pump in tank look at the 4th gen firebird set up as it will give you alot of ideas , ( image is large )

    being immersed they are quiet , the pump stays cool and will last longer ( running a intank style pump dry for a second or two is what kills them not the crud ) , you will have to change out the pumps to the lower TBI units as these run at 65 PSi vs the 14 psi

    for tank insulator we use a strip of heavy duty rubber truck mudflap . Pain to cut . but last for years . DO NOT use cloth as it traps the dust and salt dust on the roads and will cause corossion if it gets wet , if you want to go fancy go to a heavy truck dealer and they have tank insulator materials there . but a cheap $20 or roadside killed truck mudflap will make lots of insulators . ( farm and fleet has them )

    fuel inlet should be 2" max ( nozzle is 3/4" O.D.) and you should have a vent on the farthest portion of the tank from the fill to the fill tube near the top so it will not trip the filling nozzle while filling it up . and the fill should be in the center of the tank not on the ends as the sloshing can pop the cap off unless you have a mechanical locking style cap that trucks use ( and you will then have to vent the tank ) , a in tank baffle is not necessary unless the tank is long , deep and narrow , and then it should be near the pump pick up point in the center ,
    for a drain 1/2 NPT should suffice , try to make the bottom of the tank lower near this point . you do not want a flatbottom tank as it will oil can and drive you nuts with the sound , try to put ribs across the bottom or a crease to help this and if you this try to put the drain at the end and of the crease and pitch the tank towards the drain ( the crease should also act as a dirt and water trap . ( think of it as a inverted house shape )

    as for attaching brackets to a tank your asking for trouble , either inside or out the tank should be smooth and snag free , any welds other than joints/seams should be avoided as it can start a tear if caught . and nothing should be hung on the outside
    Last edited: Mar 26, 2014
  4. HuskyV8
    Joined: Apr 30, 2010
    Posts: 534


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  5. kscarguy
    Joined: Aug 22, 2007
    Posts: 1,571


    Since in tank pumps cost $190 each, plus I'd have to fabricated two installation rings, and two internal trays, (plus there is a depth issue) I am thinking that I might be better off with one in-line fuel pump.

    Is there a brand that stands out as good quality and affordable?

    Would I have an issue with having an air-lock or starving the pump when switching tanks?
  6. stimpy
    Joined: Apr 16, 2006
    Posts: 3,547


    go to rock auto for intank fuel pumps they are the cheapest and you can choose between brands for a tbi pump you can buy a Bosch turbine style ( better than a gearrotor , for 35 bucks each ,

    as for EFI inlines never had one last , they always burn up as they cannot cool themselves good enough plus you do not want to run them dry .

    and what is your definition of a tray ??? are you talking about a fuel bucket ? the part that goes around the pump to keep it full of fuel ?? or the baffle ?

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