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Need Info on gm turbo 350 trans with lock up converter

Discussion in 'The Hokey Ass Message Board' started by cowboy1, May 28, 2008.

  1. cowboy1
    Joined:
    Feb 14, 2008
    Posts:
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    Location:
    Austin TX

    cowboy1 Member

    I just got a Turbo 350 trans out of a 81 Z28 with a lock up converter has anybody here used one?
  2. The Wizard!
    Joined:
    Nov 18, 2007
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    140
    Location:
    Stillwater Minnesota

    The Wizard! Member

    What kind of info you need? You can leave lockup off all the time. You can turn it on and off with a switch, You can get a vacuum switch to control it. What else?
  3. cowboy1
    Joined:
    Feb 14, 2008
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    Location:
    Austin TX

    cowboy1 Member

    it has a 4 pin plug on the one side of the trans. What do the wires connect to. I seen Ron Francis has a wiring kit for it and uses the spedo cable for info .
    I was told i can pull the plug out and the servo and install a freeze plug where the 4 pin connctor once was but, i still need to use the lock up converter due to diffrent ionput shaft . Is that all true?
    I like the idea of having somewhat of an overdrive trans.
  4. treb11
    Joined:
    Jan 21, 2006
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    1,969
    Location:
    Houston, Texas

    treb11
    ALLIANCE MEMBER

    its not an overdrive (final is still 1:1), just a locking converter to eliminate slippage. if you do away with the plug, you do away with the locking feature. basically the plug goes to a vacuum switch (I have one if you need it) that only locks up the converter under highe vacuum i.e. at highway speeds. wiring diagram from an 81 chevy pickup will show whats needed. I don't think the wiring kits for the 200R4 / 700R4 will help hook this one up
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  5. Retrorod
    Joined:
    Jan 25, 2006
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    Location:
    Simi Valley, Calif.

    Retrorod
    ALLIANCE MEMBER

    It'll only lock in high gear. You can wire it through a simple toggle switch and a low vac. switch for unlocking under a load. I'll see if I can find the GM part number we used to use on those things when they were new. When a customer complained of "chuggle" at lower speeds in high gear we used to wire in that vac. switch to "open" the circuit when the manifold vac dropped below 10".

    Not a good idea to just leave it unlocked, a 350C tends to run a bit hot if not allowed to lock up.....they run real cool when locked.
  6. cowboy1
    Joined:
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    Location:
    Austin TX

    cowboy1 Member

    Thanks for the info guys
  7. Dirty2
    Joined:
    Jun 13, 2004
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    8,899
    Location:
    Zip City, Texas 75180

    Dirty2 Member

    I had a lock up 350 in my wagon and when you locked up the converter is was like a OD.
  8. F.O.G
    Joined:
    Oct 31, 2006
    Posts:
    115
    Location:
    Pacific,Mo

    F.O.G Member

    Drops RPM approx 200-250 when locked. Toggle switch for lockup is the way
    to go. Lots of problems with shuffling when they came out (-78) I think. You can adjust lockup point by adjusting allen screw in the lockup switch on valve
    body by turning clockwise (allen may be covered with plastic that must be scraped off). Can be turned in until it bottoms if the conv clutch starts chattering and the it works like no lockup is present. Won't run too hot.

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