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Technical Flathead I. D. please

Discussion in 'The Hokey Ass Message Board' started by wheeldog57, Feb 26, 2024.

  1. wheeldog57
    Joined: Dec 6, 2013
    Posts: 3,173

    wheeldog57
    Member

    I made a deal on an unseen flathead. My pal said he pulled it out of a 1950 big truck then had it rebuilt by a local, reputable machine shop. Yesterday we got it out of it's hiding spot. It definitely was rebuilt, new adjustable lifters and minty clean in valley. Maybe I got lucky. 20240226_183420.jpg 20240226_183431.jpg 20240226_183441.jpg 20240226_183454.jpg 20240226_183512.jpg 20240226_195100.jpg
    I took a few pictures, any help would be appreciated.
     
    41 GMC K-18 and VANDENPLAS like this.
  2. wheeldog57
    Joined: Dec 6, 2013
    Posts: 3,173

    wheeldog57
    Member

    This is where we extracted it from 20240225_174359.jpg 20240225_195205.jpg
     
  3. Los_Control
    Joined: Oct 7, 2016
    Posts: 1,141

    Los_Control
    Member
    from TX

    Simply is a 8BA that everyone has..... you can tell by the timing cover ..... probably better off to trade it foe something earlier.

    I can offer free shipping if you want to send it.
     
    Budget36 likes this.
  4. Ziggster
    Joined: Aug 27, 2018
    Posts: 1,752

    Ziggster
    Member

    Very nice! Looks like you’re no stranger to flatheads. Lol! Are those grade 5 head bolts?
     
    wheeldog57 likes this.

  5. Someone needs to help the man clean / re-arrange. On the left i see the wheels/rims stacked with rags between so his intentions must be good but the other stuff is overwhelming.
     
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  6. AVater
    Joined: Dec 9, 2008
    Posts: 3,151

    AVater
    ALLIANCE MEMBER
    1. Connecticut HAMB'ers

    Wheeldog, Great find. Thankfully the seller remembered it was there. One quick point: one head marked EAB from a car and the other 8RT from a truck. IIRC, they may have different compression ratios but this can be researched pretty quickly to see if it’s consequential.

    Appears to be painted Mercury color. Realize it’s just paint but Wonder if there could be a 4” crank hiding in there.
     
    Last edited: Feb 27, 2024
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  7. 42merc
    Joined: Dec 19, 2010
    Posts: 896

    42merc
    Member

    Grade 5 is OK, they are only torqued to 55 lbs.
     
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  8. squirrel
    Joined: Sep 23, 2004
    Posts: 56,041

    squirrel
    Member

    that is a full-on hoarder.

    Nice score, the engine should make some old hot rod happy again
     
    wheeldog57 likes this.
  9. adam401
    Joined: Dec 27, 2007
    Posts: 2,857

    adam401
    Member

    Ron your engine has one high compression head and one low compression head. Late flathead heads from low compression to high are:
    8cm, 8rt, 8ba, EAC,EAB. so basically you have an 8ba for the sake of discussion. It would be nice to pop a set of matched EAB heads on there.

    It would be helpful to see inside anyway. See what size pistons and check the stroke for a 4” crank. Even if it’s 3 and 3/4 you’ll have fun with it. Good luck
     
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  10. wheeldog57
    Joined: Dec 6, 2013
    Posts: 3,173

    wheeldog57
    Member

    Thanks for the input fellas. I appreciate the heads up on the heads, haha. Tonight I pull the heads and pan.
     
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  11. wheeltramp brian
    Joined: Jun 11, 2010
    Posts: 2,599

    wheeltramp brian
    Member

    I've got one low compression and high compression head and the thing runs smooth his silk and I don't think it makes much of a difference.
     
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  12. wheeldog57
    Joined: Dec 6, 2013
    Posts: 3,173

    wheeldog57
    Member

    I pulled the heads. .100 over pistons and 3.75 stroke. Minty minty clean and no cracks, I'm happy. Do these measurements make 255ci? 20240227_184459.jpg 20240227_184425.jpg 20240227_200059.jpg
     
  13. squirrel
    Joined: Sep 23, 2004
    Posts: 56,041

    squirrel
    Member

    looks better with all that aluminum on top!
     
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  14. Model A Gomez
    Joined: Aug 26, 2006
    Posts: 1,695

    Model A Gomez
    Member

    The 255 Merc has a 4" stroke but looks like you bought a nice motor! To run the early heads you have on it you have to plug two water passages in the block and one on the head. The two holes in the water jackets are at the front of the engine, you can see them in the pictures, 1/8' brass plugs just have to run a tap in and put a little sealer on them.

    f3.jpg f4.jpg plugs.jpg
     
  15. AVater
    Joined: Dec 9, 2008
    Posts: 3,151

    AVater
    ALLIANCE MEMBER
    1. Connecticut HAMB'ers

    My math tells me you’re now at 255 having picked up the additional 16 CI with the larger bore. Mercury CI with a Ford crank.
     
  16. wheeldog57
    Joined: Dec 6, 2013
    Posts: 3,173

    wheeldog57
    Member

    Scored another EAB head and sent my Offenhausers to the shop for a spark plug heli coil. So, i have options.
    F- that, im putting the aluminum heads on. What are your thoughts? 20240226_195015.jpg 20240227_200012.jpg
     
  17. AVater
    Joined: Dec 9, 2008
    Posts: 3,151

    AVater
    ALLIANCE MEMBER
    1. Connecticut HAMB'ers

    EAB heads are pretty good. Aside from the looks, the aluminum heads may not get you much improvement. After looking all over for a pair of Ford made aluminum heads for my Mercury motor without success, I decided to mill a bit off and aluminum coat the cast iron Mercury heads I had.
    IMG_1819.jpeg IMG_3727.jpeg
    BTW: is that other flathead your second?:rolleyes:
     
  18. 19Fordy
    Joined: May 17, 2003
    Posts: 8,047

    19Fordy
    Member

    Be sure to use the correct distributor that fits your timing cover.
    One cover fits the short shaft distributor.
    Another fits the long shaft distributor.
     
    wheeldog57 likes this.
  19. JD Miller
    Joined: Nov 12, 2011
    Posts: 2,244

    JD Miller
    Member

    Which head is the low compression? :confused: They look the same best I can tell from he pic

    [​IMG]
     
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  20. 19Fordy
    Joined: May 17, 2003
    Posts: 8,047

    19Fordy
    Member

    First, remove the head gasket and clean the surface.
    One indicator of which head has the higher compression would be to measure the depth of the combustion chamber at the same location in each head and see if there is a difference.
    Another (and better) way would be to install the spark plugs and then fill each combustion chamber with water, keeping track of how many cc's water it takes to fill the chamber. More water means lower compression.
     
    Last edited: Mar 12, 2024
  21. safetythird
    Joined: Feb 26, 2014
    Posts: 281

    safetythird
    Member

    Mine :p

    Nice score Wheeldog!
     
  22. Hillbilly Werewolf
    Joined: Dec 13, 2007
    Posts: 510

    Hillbilly Werewolf
    Member

    What shape is the combustion chamber on the Offy heads? If the EAB heads can be milled a little and yield a similar compression ratio, I would expect the factory chambers to flow better than the aftermarket ones. Even if compression comes out a touch lower, the extra flow might give more power where you want it.

    A lot to study and check. Piston to dome clearance, valve to head clearance, quench. Hard to guess, harder to know what is best.
     
    wheeldog57 likes this.
  23. wheeldog57
    Joined: Dec 6, 2013
    Posts: 3,173

    wheeldog57
    Member

    Thanks for the input guys, I'm learning as I go. @JD Miller the head on the right is the EAB, took me a minute to see the difference between the two. The 8RT is deeper but only by a little.
    I also learned that 59AB flywheels do not fit 8BA (I got to do that twice) lucky I have a spare complete motor. I also learned that the water pumps and belt set up I was using will interfere with the 8BA distributor so my radiator will be more forward, and look guffy! @19Fordy thank you for the distributor and front cover Intel, that'll save me some aggravation.
     
    leon bee likes this.

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