1977 Johnson 2 hp Piston ring gap

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  • February 21, 2018 at 7:01 am #9270
    PugetSoundBoater
    Participant

      I have temporarily misplaced my ’77 2 hp manual. Anyone know the ring end gap for .030 oversize rings?

      I want to thank Dan A. in Tennessee for arranging the boring of the block to .030 over by his friend Jason White at:
      Jay’s Block Shop in Sparta,TN He did a great job!
      Thanks to Dan and Jason!
      Jim PSB

      "Some people want to know how a watch works, others just want to know what time it is"
      Robbie Robertson

      February 21, 2018 at 3:39 pm #71422
      The Boat House
      Participant

        Hastings recommends a MINIMUM of .0035
        gap per inch of cylinder diameter.

        February 21, 2018 at 4:34 pm #71424
        fleetwin
        Participant

          US Member - 2 Years

          Jim
          Sorry, don’t have a 1977 manual. But, the 1979 manual prescribes the ring end gap to be: .015" min-.025" max
          The 1972 manual prescribes: .005" min-.015" max.
          So, I guess we better find the correct 1977 manual to be sure.
          I am assuming you are using OMC piston and rings. If not, I would look for the end gap recommendation from the manufacturer of the parts you are using….

          February 22, 2018 at 12:05 am #71435
          PugetSoundBoater
          Participant

            Fleetwin-I am using OMC .030 piston and rings. Guess i’ll have to start digging through a large stack of assortment of boxes till i find the manual. Thought one of us would have the info more handy. Hope the info is in the manual covering .030 ring gap.Thanks, Jim PSB

            "Some people want to know how a watch works, others just want to know what time it is"
            Robbie Robertson

            February 22, 2018 at 10:17 pm #71450
            Mumbles
            Participant

              I found the specs for your motor and for the ring gap it says 0.025 max and 0.015 minimum. New rings these days don’t usually need filing to fit and their gap should be towards the lower spec right out of the package.

              February 23, 2018 at 6:39 am #71458
              PugetSoundBoater
              Participant

                Thanks for all of your responses.
                Jim PSB

                "Some people want to know how a watch works, others just want to know what time it is"
                Robbie Robertson

                February 23, 2018 at 1:39 pm #71463
                jerry-ahrens
                Participant

                  US Member

                  I have a 1974 manual that say’s .005 -.015 is acceptable. If that helps any…

                  February 23, 2018 at 4:15 pm #71470
                  Mumbles
                  Participant

                    Jerry’s numbers seem more reasonable. I double checked my source and that’s what it said, 15 to 25 but doesn’t seem right. It could have been a typo. If you have a dealer nearby, they should be able to confirm the proper gap size for you.

                    February 23, 2018 at 9:29 pm #71484
                    fleetwin
                    Participant

                      US Member - 2 Years

                      The ring end gap spec changed over the years, have found the tight gap spec in the early 70s manuals, the relaxed spec in the 79 manual…

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