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How to tell the difference between a 318 and 340

Engine Issues

  1. David B

    David B Well-Known Member

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    I bought my 1970 Barracuda used. the fender tag said it came with a 318 but the air cleaner cover says 340 four barrel. How can I tell the difference? I'm having the engine pulled for overhaul so access to the block # should be easy.
     
  2. djais1801

    djais1801 Well-Known Member

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  3. 340challconvert

    340challconvert Well-Known Member

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  4. gzig5

    gzig5 Well-Known Member

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    A 340 generally pushes you further back into your seat than the 318......
     
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  5. Hemivision

    Hemivision Member

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    It's cast into the right hand side of the block in my experience
     
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  6. 340challconvert

    340challconvert Well-Known Member

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    upload_2020-1-15_7-23-17.png
    David, look for a number on the driver's side of the block, front, right below the head. A 70 engine would start with F.
    A 71 engine would start with G. The next letter is where the engine was assembled, followed by the cubic inches engine size.

    Check out the link I posted above; it has actual pictures of number ID locations
    "How to ID a small block engine block"

    It will give you all the information you need with photo locations
    Dino2 (2).gif
     
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  7. David B

    David B Well-Known Member

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    Thank y'all for your help.
     
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  8. volunteer

    volunteer Well-Known Member

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    It's cast into the Left-hand side of the block - large numbers - basically behind the starter. You can read it with a good light and a mirror, as necessary. Either 273, 318, 340 or 360 will be displayed - then a dash (-) and single number.
    ie: The 340 casting number will be 2780930-340-3.
     
    Last edited: Jan 22, 2020
  9. Hemivision

    Hemivision Member

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    Sounds good to me.. just a slip...
     
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  10. Edward Hackett

    Edward Hackett Member

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  11. Edward Hackett

    Edward Hackett Member

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    My 1968 340.
    All Mopar small blocks are similar.

    2DD030E0-987F-464F-ADD8-63031450EC6F.jpeg

    3CAAD5BF-5545-4086-BCEB-619DBBDFDBB2.jpeg

    18E3E817-38F9-4FA3-A2FA-0DA7905E2AC4.jpeg

    199C1C6C-37EE-4647-BBD2-12CDB1DBBE5C.jpeg

    CF467890-5E18-4C49-B271-CB07C74AB23E.jpeg

    B53BC30F-6E52-49DB-9BED-EAE0C67B90B6.jpeg

    8F9FA542-7BDD-44F1-A4B0-21368CC6F483.jpeg
     
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  12. Edward Hackett

    Edward Hackett Member

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    The last two photos are the casting date, and even what shift cast it at the plant.