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Technical 59A rear main cap/seal

Discussion in 'Traditional Hot Rods' started by funkfords, Sep 28, 2024.

  1. funkfords
    Joined: Sep 18, 2010
    Posts: 76

    funkfords
    Member
    from IL

    I bought a 59A block and the rear main cap doesn't have the extended area for the seal. The cap is like an 8BA rear main. The oil pan is the standard 59A oil pan. Is there a pot metal seal hold that is used?
     
  2. Ziggster
    Joined: Aug 27, 2018
    Posts: 3,010

    Ziggster
    Member

    Some pics of the rear cap on my 59A.

    4CF9BBA8-8AB9-4DF8-9ADD-7F07E4B18271.jpeg
    A741F1DB-AE61-4499-B920-C263CBA18F49.jpeg
     
  3. funkfords
    Joined: Sep 18, 2010
    Posts: 76

    funkfords
    Member
    from IL

    Here are some actual pictures of my block main cap and the oil pan.
     

    Attached Files:

  4. The 39 guy
    Joined: Nov 5, 2010
    Posts: 3,776

    The 39 guy
    Member

    I am not sure exactly what you are asking for here but when I built my 59 L flathead 13 years ago I used an 8BA crank which required using an 8BA rear main cap if I remember correctly. Since i was using a 59 series oil pan that complicated the seal arraignment. So I asked a lot of questions here on the HAMB. If you go to the link below you will find page 104 of my build thread which deals with this question. On page 104 you will find a link to a HAMB thread that I asked and received a lot of information on rear main seals. Bruce Lancaster was very helpful but sadly is no longer with us. Possibly some of people that answered my question will be able to help you.

    https://www.jalopyjournal.com/forum...upe-for-uncle-mike-build-thread.949053/page-4

    This link helped me with the seal questions.
    http://www.jalopyjournal.com/forum/threads/flathead-crank-shaft-questions.533812/
     
  5. funkfords
    Joined: Sep 18, 2010
    Posts: 76

    funkfords
    Member
    from IL

    Sorry, I'm not very good explaining this. In the pictures of my block with the rear main cap installed there is no provision for a seal on the main cap. Also my oil pan (also pictured) has no provision for any type of seal. I'm just trying to figure out if I have the wrong main cap or is there something I'm missing that will holds the seal? I hope this makes sense.
     
  6. wheeltramp brian
    Joined: Jun 11, 2010
    Posts: 3,351

    wheeltramp brian
    Member

    That looks very odd. Looks like somebody cut off the main cap.Or it's the wrong one completely Perhaps a mix of wrong parts.
     
  7. Simple: Somebody installed a later 49-53 rear main cap (which is totally wrong) and you appear to have the correct oil pan. You'll need to pick up a 39 - 48 rear main cap, and a top (pot metal) seal plate.

    You might also find that ALL of the main caps are from a 49-53 engine - which means the bearing TANGs will be wrong as well. I think I can see the center main cap - and it also looks like an 8BA cap. I would pick up a complete set of 39 - 48 main caps. You might contact VanPelt or ThirdGen to see if they have some spares.

    Important: You can't just swap in different main caps from another block without taking the block to a machine shop and having them check the mains afterwards. It may need to be align-bored and then honed when you put non-original caps on it.

    If this in an unknown block, then I would have the block magged, sonic tested and pressure tested before I invested in the main cap work. If the block is bad, you'll have wasted a bunch of money on it.

    Best of luck!
    B&S
     
    Last edited: Sep 30, 2024
    alchemy likes this.
  8. alchemy
    Joined: Sep 27, 2002
    Posts: 22,760

    alchemy
    Member

  9. funkfords
    Joined: Sep 18, 2010
    Posts: 76

    funkfords
    Member
    from IL

    Okay, thank you.
     

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