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Technical 51 Merc flathead 8CM to 8BA swap

Discussion in 'The Hokey Ass Message Board' started by solo_909, Oct 13, 2018 at 9:07 PM.

  1. solo_909
    Joined: Apr 9, 2006
    Posts: 1,703

    solo_909
    Member

    Hey fellas,

    So my 51 Mercs 8CM is toast. I found an 8BA that I bought but my question is what parts will I need to swap to allow it to fit back into my Merc? I assume the oil pan but what else?

    Any help will be greatly appreciated. Yes I know the 8CM is a stronger motor, yes I know I can just rebuild it, but I don’t have that kind of money and I don’t want to haha. I found a smoking deal on a rebuilt 8BA so I’m going to just use it.

    Thanks,
    George
     
    Last edited: Oct 13, 2018 at 9:20 PM
  2. Dirty Dug
    Joined: Jan 11, 2003
    Posts: 3,441

    Dirty Dug
    Member

    You'll need to swap the water pumps as well.
     
  3. Mr48chev
    Joined: Dec 28, 2007
    Posts: 23,351

    Mr48chev
    ALLIANCE MEMBER

    That's about it but swapping intake and carb would make it easier to hook the linkage up. The price of an intake gasket to put the Merc intake and carb on the 8BA might save a bit of head scratching.
    Should be a one day or one weekend swap if you don't get into the "while I am at it" thing.
    My 51 Merc had 8BA heads and I think an 8BA engine with the Merc carb and intake on it when I bought it in 1963. I didn't know 8BA from 8CM in those days.
     
  4. solo_909
    Joined: Apr 9, 2006
    Posts: 1,703

    solo_909
    Member

    Awesome, thanks guys. Will the bellhousing and trans bolt up?
     
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  5. Dirty Dug
    Joined: Jan 11, 2003
    Posts: 3,441

    Dirty Dug
    Member

    Yes, the blocks are the same, only the bore is different.
     
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  6. solo_909
    Joined: Apr 9, 2006
    Posts: 1,703

    solo_909
    Member


    Perfect! One other question, will I have to pull the trans and motor or can I just pull the motor?
     
  7. Dirty Dug
    Joined: Jan 11, 2003
    Posts: 3,441

    Dirty Dug
    Member

    Afraid I can't answer that, never put a flat motor in a stock car it came from, only hotrods, but someone will have advice on that.
     
  8. tubman
    Joined: May 16, 2007
    Posts: 3,674

    tubman
    ALLIANCE MEMBER

    Not entirely correct. Both the Ford and Mercury engines have a 3 3/16" bore; the difference is the stroke. The Mercury has a 4" stroke, while the Ford is 3 3/4". Before you scrap the Mercury engine, you should have the crankshaft checked to see if it is OK. Just about any engine rebuilding shop should be able to check that for you, and also determine if it can be salvaged by turning the journals undersize. Merc cranks are very desirable.

    I have not done the "Ford into a Merc" swap, but I have done a "Merc into a Ford". It was easier to pull the engine and transmission as a unit.
     
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  9. Dirty Dug
    Joined: Jan 11, 2003
    Posts: 3,441

    Dirty Dug
    Member

    Yeah, you are right, sorry for the incorrect info.
     
  10. solo_909
    Joined: Apr 9, 2006
    Posts: 1,703

    solo_909
    Member


    Okay, thank you!
     

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