12 vs 13 Torque Converter

Discussion in 'The "Juice Box"' started by BRUCE ROE, Nov 25, 2020.

  1. BRUCE ROE

    BRUCE ROE Well-Known Member

    Does anyone know, if a 13 inch switch pitch Torque Converter will fit on a
    mid 60s 2 speed trans originally equipped with a 12 inch switch pitch TC?
    I know the 12 will fit OK on a 3 speed originally equipped with 13 TC, but
    not sure the 2 speed bell housing has enough clearance for the bigger 13
    inch TC. No 2 speeds here, or I could try it myself. Bruce Roe
     
  2. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD" Staff Member

    Same bell housing bolt pattern. Wouldn't it have to fit? The 68-69 ST300 probably used a 13" behind the 350 V8 in the Skylark. I say yes.
     
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  3. TrunkMonkey

    TrunkMonkey Well-Known Member

    Hi Bruce.

    I have both ST300 and ST400 sitting in the garage, went and checked and the bell housings are the same dimension. (they are side by side, and the bells appear identical, to the point of the line of the pump area)
    I would need to pull a car out of the garage to physically put the ST400 converter in the ST300 to verify.

    Can you wait until Friday? (It's pouring rain, the '64 has the top down and I am heading to a friend's to gobble turkey)

    Larry,
    The ST300 is out of my 1964 Skylark.

    I also have the ST300 from my 1968 Skylark and it has a 12 inch converter.
     
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  4. BRUCE ROE

    BRUCE ROE Well-Known Member

    Did you try the 13 inch in the 2 speed? thanks, Bruce
     
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  5. TrunkMonkey

    TrunkMonkey Well-Known Member

    I did not, due to rain.
    It's clear today, so I will get that done in a bit and update this post. (it's noon. I should have a reply by 2PM)

    I do not have the 12" available to put in the case and compare, but I will do my best to get a WAG on clearances.
    Maybe put frogs in there and see how much their eyes bug out or something sciency...



    The frog sez:
    The tightest clearance is on the back side (shoulder) of the converter to the case. It is 3/16" and that is the "diagonal lines" on the converter shell to the case. This is with full set back and converter to pump gear lugs fully seated. So additional clearance when converter is stacked up and bolted to the flexplate.

    The converter bolt boss face depth from the (to block) mounting surface of the case is 3/4" at full seat position.

    The mounting surface of the flex plate plane (facing converter) is 15/16" from the back of the block (to bell) mating surface.

    upload_2020-11-28_15-56-38.png
     
    Last edited: Nov 28, 2020
  6. BRUCE ROE

    BRUCE ROE Well-Known Member

    Good picture, thanks. Bruce Roe
     

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