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Technical First post! Th350 trouble

Discussion in 'The Hokey Ass Message Board' started by Grandpacharli, Feb 17, 2020.

  1. Grandpacharli
    Joined: Feb 17, 2020
    Posts: 27

    Grandpacharli

    Not sure if this is the right category to ask but a little introduction first.

    I live in the Uk and recently imported my 63 c10. I have fitted everything myself etc crate 350 with th350 trans . The trans was second hand but in good faith that it had been rebuilt ! I have never driven a 350 350 onboard before so I’m unsure of the characteristics of the trans but I’m sure I have a problem. Basically when I accelerate from a stop it’s sluggish unless I floor it (WOT) then it goes really well ! Kick down is installed correctly . Engine pulls strong correct amount of fluid and measured whilst in park after shifting through all gears several times.

    Any help guys? Or is that normal


    [​IMG]


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  2. squirrel
    Joined: Sep 23, 2004
    Posts: 55,870

    squirrel
    Member

    It's pretty hard to tell from this side of the ocean, what exactly is going on. Is the engine sluggish, no power? or is the transmission in the wrong gear? or what?
     
  3. If you manually start in low,and shift up manually would it perform better,or is it the same?Could be your not starting off in low in the automatic mode,and its sluggish because your in 2nd,and when you push hard on the throttle it forces a down shift ,and gives more power.Just a thought.Is the vacuum line to the module on the transmission good,and hooked to a correct port on the engine?
     
  4. squirrel
    Joined: Sep 23, 2004
    Posts: 55,870

    squirrel
    Member

    If it's not getting vacuum, it will shift late, so that's not likely to be the problem. Although it is important that it be connected properly.
     
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  5. Grandpacharli
    Joined: Feb 17, 2020
    Posts: 27

    Grandpacharli

    I haven’t tried shifting in low , although it does select all gears fine , it’s acting fine it runs it drives etc reverse is fine , idles at 750 the drops to 550 . I guess it could be downshifting when I floor it hence why it pulls fine but that’s normal due to the kick down cable , it’s just weird it being so sluggish at accelerating from a stop. You have to rev it high to move fast pulling off is okay once the brake is released it will get up to speed eventually



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  6. squirrel
    Joined: Sep 23, 2004
    Posts: 55,870

    squirrel
    Member

    I encountered one case where the stator in the torque converter was slipping, so it was very sluggish getting moving. A torque converter normally provides up to about 2:1 torque increase as the car gets moving, so if the stator is freewheeling, it will act like a fluid coupling, not a torque converter.

    edit: this was with a stock torque converter, and it didn't really act like a high stall converter, it didn't increase RPM, it just didn't have any torque

    Again, it's pretty hard to tell from here, exactly what is going on. The manual low test is a good idea, so at least you know it's starting in first gear.
     
    Last edited: Feb 17, 2020
  7. Grandpacharli
    Joined: Feb 17, 2020
    Posts: 27

    Grandpacharli

    That’s the trouble I can’t jump into another vehicle to understand what’s normal ! Engine is fine new carb and ignition setup . It’s almost like a slipping but then when you boot it it pulls like train ! Weird can’t understand it


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  8. Grandpacharli,

    Did you get any specs on the converter? Ie...advertised stall speed? If not, you should apply the foot brake and floor it to see what rpm (does the truck have a tachometer? If not, you might want to think about getting one) the converter flashes to. Your description kinda sounds like a stall converter.

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    squirrel likes this.
  9. Grandpacharli
    Joined: Feb 17, 2020
    Posts: 27

    Grandpacharli

    That’s possible I’ll try the low and start from their , I’ll also try and get a video maybe with the tach and speedometer in view . Thanks


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  10. Gramps , You're going to have to do more road testing. The knowledge is here, but we need more accurate feedback.
    Put it in manual low . Bring it up to about 30 whatevers. Let off the gas and see if you've got distinct engine braking. Then give it some petrol and upshift it. See if you detect a second gear shift...Report back , and we'll go from there.
     
    sleepchamber and squirrel like this.

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