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Technical Aluminum gas cap needed

Discussion in 'Traditional Hot Rods' started by 34Joe, Mar 23, 2017.

  1. 34Joe
    Joined: Nov 27, 2010
    Posts: 120

    34Joe
    Member

    Here is my problem. I have a stainless steel Rock Valley 15 gallon gas tank in my 1934 Ford Coupe. It has an aluminum gas cap with an "O" ring inside. The tank is an older unit with a bottom feed. The gas cap fits a two and a half inch neck. It has worn out, and it has fine thread. Upon calling Rock Valley I was told that they no longer make units with fine thread caps ,and that the cap I need is no longer available. Has anyone got a cap . Any info appreciated.
     
  2. oj
    Joined: Jul 27, 2008
    Posts: 6,037

    oj
    ALLIANCE MEMBER

    Did you look at the Moon caps?
     
  3. Murphy32
    Joined: Oct 17, 2007
    Posts: 657

    Murphy32
    ALLIANCE MEMBER
    from Minnesota

    upload_2017-3-23_8-21-26.png

    -Oops, wrong neck size.
     
  4. Sheep Dip
    Joined: Dec 29, 2010
    Posts: 1,569

    Sheep Dip
    Member
    from Central Ca

    Know anyone with a manual lathe with the ability to cut threads? Any local machine shop should be able to help you.
     
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  5. Barn Find
    Joined: Feb 2, 2013
    Posts: 2,321

    Barn Find
    Member
    from Missouri

    You might try boat parts, as well.
     
  6. 34Joe
    Joined: Nov 27, 2010
    Posts: 120

    34Joe
    Member

    Thanks, ill give it a try.
     
  7. 34Joe
    Joined: Nov 27, 2010
    Posts: 120

    34Joe
    Member

    Got one from them, coarse thread and only two and a quarter inches wide.
     
  8. 34Joe
    Joined: Nov 27, 2010
    Posts: 120

    34Joe
    Member

    Moon only makes a two and a quarter inch gas cap/thread unknown.
     
  9. porknbeaner
    Joined: Sep 12, 2003
    Posts: 40,902

    porknbeaner
    Member

    What is worn out on the cap? if all it needs is an O-Ring just ring it.
     
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  10. 47streamliner
    Joined: Feb 24, 2014
    Posts: 157

    47streamliner
    Member
    from Huntley il

    If it's the threads that are worn take it to a machine shop to recut the threads


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  11. dreracecar
    Joined: Aug 27, 2009
    Posts: 2,689

    dreracecar
    Member
    from so-cal

    2 choices--- 1- have 2 new caps machined (spare) or 2- remove the tank, clean the crap out of it and weld a new filler assy on it with somthing you can get parts for. Not a big deal to do either one
     
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  12. Richard Head
    Joined: Feb 19, 2005
    Posts: 493

    Richard Head
    Member

    I think Tanks Inc. carry those caps.

    Dave
     
  13. 34Joe
    Joined: Nov 27, 2010
    Posts: 120

    34Joe
    Member

    Threads are tired, as the cap is aluminum and the tube neck on the tank is stainless steel.
     
  14. 34Joe
    Joined: Nov 27, 2010
    Posts: 120

    34Joe
    Member

    Tanks caps are two and a quarter inches, I need two and a half inches.
     
  15. rjones35
    Joined: May 12, 2008
    Posts: 851

    rjones35
    Member

  16. KoolKat-57
    Joined: Feb 22, 2010
    Posts: 2,748

    KoolKat-57
    Member
    from Dublin, OH

  17. gimpyshotrods
    Joined: May 20, 2009
    Posts: 15,891

    gimpyshotrods
    Member

    It is. Fuel Safe makes competition sanctioning body regulation compliant components for racing fuel systems, not random caps for hot rods. The fuel cell in my Porsche was about $2000, two decades ago.
     
  18. 34Joe
    Joined: Nov 27, 2010
    Posts: 120

    34Joe
    Member

    Contacted them,they have the right size, but are coarse thread. They are going to check and see if they have any older stock which was fine thread. Appreciate the info.
     
  19. 34Joe
    Joined: Nov 27, 2010
    Posts: 120

    34Joe
    Member

    Fifty dollars is nothing compared to having to buy another $800.00 gas tank.
     
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  20. rjones35
    Joined: May 12, 2008
    Posts: 851

    rjones35
    Member


    Right on! That's a step in the right direction!
     
  21. rjones35
    Joined: May 12, 2008
    Posts: 851

    rjones35
    Member

    What about looking into an adapter, from your tank to whatever the common cap is now? Might have to have one made, but then you wouldn't have this problem again.
     
  22. 34Joe
    Joined: Nov 27, 2010
    Posts: 120

    34Joe
    Member

    The gas tank neck sticks out of the rear sheet metal several inches and as it is the gas cap is near the liscence plate assembly, not much room at all to work with. Appreciate the idea.
     
  23. oldolds
    Joined: Oct 18, 2010
    Posts: 2,671

    oldolds
    Member

    Could you get one of the ones with the smaller diameter and have it machined out to what you need? Is there enough meat there to do that? If you try to rethread your old one you will lose too much material.
     
  24. 34Joe
    Joined: Nov 27, 2010
    Posts: 120

    34Joe
    Member

    The next size down in this style cap is two and a quarter inches in size, of no use as I need two and a half inches. Not enough material on a two and a half inch coarse thread cap to attempt to change it to fine thread.
     
  25. oldolds
    Joined: Oct 18, 2010
    Posts: 2,671

    oldolds
    Member

  26. 34Joe
    Joined: Nov 27, 2010
    Posts: 120

    34Joe
    Member

    They don't have the size I need, or the thread, and jump from two inches to three and four inches in size. Appreciate the info.
     
  27. 34Joe
    Joined: Nov 27, 2010
    Posts: 120

    34Joe
    Member

    Fuel Safe just got back to me, they don't have any of their early fine thread caps left in stock. They no longer use them. Appreaciate the info.
     
  28. ghornbostel
    Joined: Jan 3, 2012
    Posts: 131

    ghornbostel
    Member

    Joe
    You need to determine what the thread lead is on the tank (threads per inch). Next you need to determine the diameter (actual) is of the filler. To get a close measurement you will probably need three wires that when they are put into the threads, one wire on one side and two wires on the other, they stand proud of the thread. Measure the diameter over these wires and the actual thread depth of can be determined from that. Now your machinist can cut a inside thread to fit without having the filler neck. If you have three drill bits the same diameter that works. You can measure over the tops of the threads on the filler but that pipe was probably under 2 1/2 to begin with which is why the threads in the cap don't work now as they had very little engagement to begin with.
    Hope this is helps
    Greg

    Sent from my iPhone using The H.A.M.B. mobile app
     
  29. ghornbostel
    Joined: Jan 3, 2012
    Posts: 131

    ghornbostel
    Member

    Joe
    Quick and dirty would be to wax the crap out of the filler tube threads and clean the cap with acetone. Mix epoxy and apply to the inside if the cap and put it on the filler tube. Just make sure you put plenty of wax on the filler threads. Teflon pipe tape would probably work better but only two or three wraps.
    Just thinking.
    Greg



    Sent from my iPhone using The H.A.M.B. mobile app
     
  30. 39cdan
    Joined: May 11, 2016
    Posts: 41

    39cdan

    Is the "O" ring bad or the treads? You might try a tread file.


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