340 seems to be locked up

Small Block Mopar Engine

  1. dancinwulf

    dancinwulf Well-Known Member

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    I dropped a rebuilt 340 into my 70 Duster we turned it over by hand to bolt in the torque converter. Now that everything is together it seems to be locked up. Checked the starter relay and the starter they both seem to be functioning right then tried to move the flywheel by hand seems to be stuck. Could I have connected the 727 linkage wrong. Help please
     
  2. furrystump

    furrystump Well-Known Member

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    So it turned over on the stand, but now in the car it won’t turn over?
     
  3. Dubob

    Dubob Well-Known Member

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    Last it moved freely was while connecting torque converter. So that’s where I’d go back to. Flexplate installed properly, meaning front and rear. Proper bolts in torque converter to flex plate, if they are not correct the bolt head will catch on block. Was the converter properly seated onto trans shafts, this can be a bear because there are two sets of splines that are engaged. If the flex plate is installed properly then you should of had to pull converter forward to bolt it up if the converter was properly engaged to trans.
     
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    • furrystump

      furrystump Well-Known Member

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      When you attached the converter was it sitting a good bit back in the transmission bell housing. Like 1/2”? So you had to turn it slightly and pull it forward so it would touch the flex plate. NOT using the bolts to move it forward?
       
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      • yellow rose

        yellow rose Doctor of Thinkology.

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        STOP NOW. Most likely you don't have the converter all they way into the pump. Stop turning it as at this point you can damage the thrust main enough that it won't fail on fire up but 5000 miles from now the thrust will be shot.

        You can tell when the converter is all the way into the pump. Number one is the converter should be so far into the tranny that it looks like it will hit the case. Number two is you should have to pull the converter at least a 1/2 inch before it meets up with the flex plate.

        If those two thing didn't happen stop and make it happen.
         
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        • yellow rose

          yellow rose Doctor of Thinkology.

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          Damn. Treed again. I am getting old.
           
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          • furrystump

            furrystump Well-Known Member

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            DuBob beat us both!!!!
             
          • yellow rose

            yellow rose Doctor of Thinkology.

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            Well I really suck because I didn't see that one. Unreal. My wife says I'm getting old but I refuse to let her win that argument even though she aint wrong!
             
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            • dancinwulf

              dancinwulf Well-Known Member

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              Yes slid it on myself and then pulled it out to connect it to the flex plate so thats why I am stumped. will pull the cover off to see if any of the bolts are touching or anything I can see.
               
            • MoparMike1974

              MoparMike1974 Well-Known Member

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              Did you try turning the crank from the front in both directions?
               
            • dancinwulf

              dancinwulf Well-Known Member

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              Will try that tomorrow thanks
               
            • 408 swinger

              408 swinger FABO Gold Member FABO Gold Member

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              TAKE DUBOB'S ADVICE!!!! Another thing to look at, if this engine build is a complete unknown, converter snout to crank register issue. Meaning, old enough, non 340 crank, that has small hub register. That will prevent the snout from "pulling into" the crank.
               
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              • 3406pk

                3406pk Well-Known Member

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                The correct bolts for convertor have thin heads for clearance. Also did you get all 4 bolts tightened & retightened. I got locked by that once. Tightened 3 bolts too much & 4th was sticking out then locked it.
                 
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                • superchargeddrt

                  superchargeddrt Well-Known Member

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                  Make sure you used the correct flexplate to torque converter bolts. I bought what looked to be the correct bolts and as it turned out they were for flexplate to crankshaft and they threaded into the holes the heads were a little bit taller causing them to jam. Just something to check.
                   
                • AJ/FormS

                  AJ/FormS 68 B'cuda fb, Form S clone ... 367/A833/3.55s FABO Gold Member

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                  So no fluids in the engine yet? Specifically no coolant.
                   
                • MoparMike1974

                  MoparMike1974 Well-Known Member

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                  I agree, if you use anything except the correct original bolts you will likely have interference issues. Thats why I said try turning the crank from the front both ways. This will tell you if a bolt head is holding it or if its a binding problem elsewhere.
                   
                • rustycowll69

                  rustycowll69 Well-Known Member

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                  stock flex plate?
                   
                • famous bob

                  famous bob mopar misfit FABO Gold Member

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                  I had this problem once , there was a (lost?) bolt that fell down in the trans. , under the convertor and wedged between the trans. and convertor teeth.
                  Talk about relief when I found it !!
                   
                • 67Dart273

                  67Dart273 FABO Gold Member FABO Gold Member

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                  ...........and if it turns out to be a converter problem into the trans, DO NOT run it before you pull the pump apart and inspect it
                   
                • dancinwulf

                  dancinwulf Well-Known Member

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                  One of the bolts for the TQ did not get tightened down completely
                   
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                  • dancinwulf

                    dancinwulf Well-Known Member

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                    Thanks for all the help
                     
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                    • yellow rose

                      yellow rose Doctor of Thinkology.

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                      Nice and easy and cheap.
                       
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                      • 4spdragtop

                        4spdragtop FABO Gold Member FABO Gold Member

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                        Nice, congrats! Thanks for update!
                         
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                        • superchargeddrt

                          superchargeddrt Well-Known Member

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                          There ya go! So glad it worked out.
                           
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