’54 Fleetwin – wont run on low speed

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  • June 15, 2020 at 11:24 pm #205857
    JOHN HOLBIK
    Participant

      I suffered the same fate as you Buc my older brother used my four years younger body as the resident spark tester.I am an electrician and have recieved many shocks in my career but none seem to compare in intensity to those of my childhood.

      June 23, 2020 at 10:07 pm #206547
      burnt-clutch
      Participant

        So I bought the spark plug tester (Lisle version) and I verified that I had spark through all ranges of the tiller handle. I installed the welch plug, and got the carb installed without incident. I ran it on the water for the first time tonight and it is much better, but I noticed a few quirks. 1st, if I take my hand off of the tiller handle, the handle gradually twists clockwise (it slows itself down) until it gets to the “Shift” marking where it dies. Is this normal, or could there be something under the flywheel that is causing this? 2nd, the motor shakes alot when it slows down past the “Start” markings. Could this be because of sloppy timing? I’m tempted to buy a OMC timing fixture thingee to make sure I am spot on, but I’m just wondering if shaky low RPMs are normal. Let me know what you think.
        -Karl

        June 23, 2020 at 10:22 pm #206548
        Buccaneer
        Participant

          US Member

          Are the spring and friction block in the twist grip in place / okay? If not, that may
          be why you motor doesn’t maintain speed when you take your hand off the tiller.

          Not sure if you mentioned the compression previously, if not good enough, all
          the tuning in the world may not help. Could be a carb issue, or ignition as well.

          Prepare to be boarded!

          June 23, 2020 at 11:06 pm #206552
          Tinman
          Participant

            US Member

            Could be coils rubbing the flywheel.

            June 24, 2020 at 10:07 am #206557
            aquasonic
            Participant

              US Member

              A shaking motor can be a symptom of a broken or expanded pinion shock absorber. Also, a good idle is not possible with this condition.

              June 24, 2020 at 10:47 am #206559
              burnt-clutch
              Participant

                Thanks again for the replies. I’ll double check the compression and take a look at the pinion shock absorber and tiller grip. For the coils, the mounting bosses on the magneto plate are boogered up and I don’t have a good lip on the boss to align the coil to. I should probably but the coil locating ring as well as a timing fixture to take the guesswork out of my ignition. So for a bigger picture question, is the ’54 Fleetwin identical to the ’57? The only schematic that I have for this motor is a ’57 that I found here – https://aomci.org/forums/topic/1957-fleetwin-7-5/ . I can tell off the bat that there are some parts listed here that are not on my motor.

                -Karl

                June 24, 2020 at 10:54 am #206560
                burnt-clutch
                Participant

                  About that compression, I tested it after I started this thread and the compression readings were actually lower than before I overhauled the motor (60 / 70). I was able to re torque the head bolts and get them a little tighter than what they were, but I haven’t re-tested the compression. Also do the fancy head gaskets with the copper rings that line the cylinder holes really improve the compression readings? The old head gasket that I took off didn’t have those copper rings. How tight can I torque the head bolts to? I torqued them to 7.5 ft #.
                  -Karl

                  June 24, 2020 at 11:04 am #206561
                  Tom
                  Participant

                    US Member

                    Maybe I missed this, but have you confirmed that the gasket at the bottom of the fuel delivery tube (inside the carburetor) is intact?

                    T

                    June 24, 2020 at 6:06 pm #206596
                    fleetwin
                    Participant

                      US Member - 2 Years

                      Like others have said, perhaps someone took the friction block and spring out from under the twist grip handle…The mag plate might be sloppy, and/or coils improperly adjusted also…I would remove the plugs and recoil, then rotate the flywheel to see if the magnets are dragging on the coils…
                      I am trying to remember the whole story on this engine, did you pull the powerhead apart? If so, I’m sure you replaced the head gasket at that point. The plain head gasket with no ring should work just fine on this low compression engine….Did you notice any problems with the block or head mating surfaces that might cause a leak? Any signs of water in the cylinders, did the head gasket appeared burned through when you removed it? I would certainly use a new head gasket, reusing an old one is not advisable. Don’t try to “over torque” the head bolts in an effort to raise compression on the low cylinder. You will end up stripping the threads and warping the mating surfaces. I would not use a foot pound torque wrench either, use an inch pound set from 60-80 inch pounds. Once the engine has been run and cooled, by all means retorque the head bolts to this recommended spec.
                      I’m “guessing” your uneven compression is not due to a head gasket issue, but sure hope I am wrong…
                      The vibration at low speeds could be many things, perhaps you can post a video of the engine running. It is hard to know if the driveshaft shock absorber is an issue without disassembling the gearcase, which I don’t recommend right now. You don’t want to pull that apart for nothing. But, I would certainly drain and inspect the gear lube….Signs of water spell trouble which might include a shock absorber problem…
                      So, just want to understand…The carburetor idle passage core plug was missing, correct? Installing a new core plug improved the idle?

                      June 25, 2020 at 10:10 am #206655
                      burnt-clutch
                      Participant

                        So the whole story is that the motor is new to me, and I started to overhaul it a few months ago. Before I started work on it I did a compression test which gave me readings of 70 / 80. I removed the cylinder head and planed it and the power head (at the top of the cylinders) before installing the new head gasket. I didn’t notice if the old head gas was burned but I replaced it for good measure. I saw some scoring at the top of the cylinders but noting else.The welch plug was never missing, I just took it out thinking that the lead shot that I mentioned at the beginning of the thread was missing. The motor does idle better than when I started this thread, – I think that I accidentally installed the high and low speed needles in the wrong places when I originally put the carb back together. I’ll do another compression test this weekend and see if the numbers are improved, and I’ll drain the lower unit oil and see if there is any water in it. So is the friction plate thingee the item that is circled in this picture? Does anyone have a link to the parts list for a ’54 Fleetwin, or is that year identical to a ’57?
                        -Karl

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