Difference between a 340 and 360 Torque converter please?

Transmission and Drivetrain Tech

  1. Veryfastdart

    Veryfastdart Well-Known Member

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    I just bought a 340 and have a SB 727 transmission. I want to mate them and I need to known which TC to use? I have a 727 trans mated to a 360 now.
    The Motor is a 1969 date coded Forged crank, has a (roughly) 1" damper on it.
    Thanks
     
  2. gregpurcell

    gregpurcell Greg Purcell

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    The 360 is a cast crank, externally balanced engine with weights welded to the factory converter. It should either have one weight tack welded on near the drain plug or two smaller weights on either side of the plug. The 69 340 is an internally balanced steel crank motor that doesn't use balance weights. If you grind the welds off carefully and remove the weights, the 360 converter will work fine on the 340
     
  3. Veryfastdart

    Veryfastdart Well-Known Member

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    Awesome
    Thank you so much!
    Now another crazy question? I cant get gas into my filler tube on my 71 Dart swinger?? It keeps kicking the gas off and if I force it in it over flows like the tank is full??
     
  4. pishta

    pishta I know I'm right....

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    try inverting the filler when you gas up. PITA but it works sometimes. I had a 57 Ford and the filler pipe was horizontal for about 12 inches behind the fold down license plate, stupid!
     
  5. Veryfastdart

    Veryfastdart Well-Known Member

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    I tried that already. Didn't work either??
     
  6. forphorty

    forphorty Well-Known Member

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    All the 340 converters were high stall. the 360 converter may or may not be.
     
  7. gregpurcell

    gregpurcell Greg Purcell

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    But not all 727 converters will interchange between the different years and "lock up transmissions" etc. The 340 converter could be higher stall BUT it MIGHT not fit into the 360 trans. We know the 360 unit is in and working so it's the easiest possibility.

    Be advised that it may be necessary to use the flex plate from the 360 on the 340 to get it to mate up correctly.
     
  8. Veryfastdart

    Veryfastdart Well-Known Member

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    gregpurcell,
    I assume you mean if I grind the weld off the 360 converter and install it on my 340? You believe if I doi that I may have to use the 360 Flex plate?
     
  9. 70bigblockdodge

    70bigblockdodge Member

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    The flexplate should not make a difference unless it is a offset balance aftermarket one (looks very different from stock)
     
  10. Veryfastdart

    Veryfastdart Well-Known Member

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    That's what I thought? Thank you
     
  11. 70bigblockdodge

    70bigblockdodge Member

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    Your 340 should be forged crank and internal balance, no weight on converter. The 72-73 340 has cast crank (converter has weight on it) it does not have same external weight as 360.
     
  12. gregpurcell

    gregpurcell Greg Purcell

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    gregpurcell,
    I assume you mean if I grind the weld off the 360 converter and install it on my 340? You believe if I doi that I may have to use the 360 Flex plate?


    The factory high stall converter sometimes used a different size flex plate than the normal stall. They only make two different sizes (10 inch and 11 inch). Chances are the converters will be the same. BUT if the 340 had a high stall with the 10 in flex plate and you wanted to remove the weights and keep the 360 converter, you would need the 11 inch flex plate that is currently on the 360 motor. Probably not an issue but in the"what could possibly go wrong" realm it should be mentioned

    Here's the two possible stock flexplates that you may encounter: Either one will bolt to either engine:
    flexplatediff.jpg
     
    Last edited: Sep 10, 2018
  13. Veryfastdart

    Veryfastdart Well-Known Member

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    Awesome info
    Thank you so much!
     
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