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  • I Left Feedback Too Soon

    I bought this old David Bradley Power Products chainsaw engine off ebay the other day. The price and shipping were both fair, and when I saw the engine it looked good as described, so I left good feedback right away. The seller shouldn't have said "it turns over nice and has good compression" though, because it was stuck. I removed the muffler and sprayed GIBBS into the piston and cylinder and finally got it to move, but I'll have to remove the cylinder and hone it out, and hope the piston and rings can be saved. The fan cover was full of mouse nest, and the mouse had chewed the kill switch wire in half.

    http://www.ebay.com/itm/Chainsaw-Tec...72.m2749.l2649

  • #2
    I can take some pictures tomorrow, but today I removed the cylinder, removed carbon, and unstuck the top ring. I can give the cylinder a light hone, and the piston and rings are good to reuse. It wasn't the piston that was stuck, but the ball bearing on the crankshaft. I oiled it and kept working it and flushing it, so now it feels good. I'll flush it some more and see how it looks.

    The points cam needs to be replaced, as it's extremely worn out from not being lubricated. The factory even has a felt wick which extends to the outside of the points housing to make oiling it very easy, but the owner still never oiled it.

    Comment


    • #3
      You sure stay busy lol
      3 ~ Tudor's
      Henry Ford said
      "It's all nuts and bolts"


      Mitch's Auto Service ctr

      Comment


      • #4
        Here are some pictures of the Power Products chainsaw engine. Picture 2 shows the badly worn points cam, just below the knife tip. Picture 5 shows the 30 tiny needle bearings that need to be installed in the connecting rod bottom end. I held them in the cap and rod with grease, but it was a bit of a trick to get those 2 parts screwed back together without dropping the cap or needles. I got lucky, and it only took 2 tries, so I can put it back together except for the points cam and parts over that. The rod has needle bearings on both ends, and the crank has large ball bearings on both ends. Picture 7 shows the felt to be oiled to lubricate the points cam. Picture 4 shows a small backyard fish pond I bought at a garage sale yesterday on my way home from the metal yard. This would make a great outdoor bath tub for these hot summer days, but I'll use it to cover projects, like this engine, from the rain and night dew.

        I was wondering if anyone knows a good cleaner to remove the crud from aluminum parts. I used gas, a knife, and a wire brush, and finally got it clean, but there must be some good spray cleaner that won't hurt aluminum.

        Also, where can I find another can of GIBBS? Thanks

        Comment


      • #5
        Originally posted by Mitch View Post
        You sure stay busy lol
        Yes, too much to do, and summers way too short. Lots of rain doesn't help either. I'd like to get caught up and take a vacation.

        BTW, on the piston rings, I make sure the ring end gaps don't end up in the port area, especially the hot exhaust port. I do the same thing with car engines and the top ring. I make sure the end gap isn't near the hot exhaust valve.

        Comment


        • #6
          Hey, speaking of rings, I have always wondered if the rings stay where you set them, or rotate around the piston while working?
          You wana look waaay far up da road and plan yer route because the brakes are far more of a suggestion than a command!

          Comment


          • Mitch
            Mitch commented
            Editing a comment
            i thought they moved

        • #7
          Originally posted by Mitch View Post
          i thought they moved
          I think they can move but don't always move. I had to overhaul a Chevy V8 back in 1967, and one of the pistons had all the ring gaps in an exact straight line, which left a line of unworn metal in that cylinder. Never saw that before or since, and never heard of it happening to anyone else. One of my chainsaws has the piston rings pinned so they can't rotate. The strange thing is they are both pinned in a straight line. Seems like a dumb way to do it.

          Comment


          • DaWizard
            DaWizard commented
            Editing a comment
            Couldn't you turn one over and have the gap wind up someplace else?

            Whoops, nm, I know better since the ring has the inside edge chamfer to allow the gas pressure to keep the ring expanded.
            Last edited by DaWizard; 09-02-2017, 11:15 PM. Reason: stupidity

        • #8
          Interesting engineering read!

          http://www.diagnosticengineers.org/j...dge%20Gaps.php

          3 ~ Tudor's
          Henry Ford said
          "It's all nuts and bolts"


          Mitch's Auto Service ctr

          Comment


          • DaWizard
            DaWizard commented
            Editing a comment
            VERY interesting.

            LOL, free burial at sea.
            Last edited by DaWizard; 09-02-2017, 11:17 PM.

        • #9
          I learned something new today. Since I have the chainsaw Power Products AH-47 engine ready, except for the worn points cam, I thought I'd borrow the cam out of my parts mower with the stuck engine. I removed the flywheel and discovered even though the engines are almost identical, the mags and cam are different. While I had the flywheel off I figured I'd check the magnetism in the flywheel, but there wasn't even a hint of magnetic pull. I'd never heard of a magnet loosing all it's strength, so I checked the mag, and found out the magnet is mounted to the mag coil. This is the first time I'd seen a small engine without the magnet in the flywheel.

          PP Parts.JPG

          Comment

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