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Home › Forums › Beginners questions › casting

Viewing 8 posts - 1 through 8 (of 8 total)
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  • 25 August 2013 at 08:12 #127813
    david simmo
    Participant
      @davidsimmo

      hi on gun metal casting(cylinders) whitch is best gunmetal to gunmetal or gunmetal to s/steel it for the pistons and bobin(vavle) thanks dave

      25 August 2013 at 08:12 #6846
      david simmo
      Participant
        @davidsimmo

        cylinder

        25 August 2013 at 09:48 #127819
        Sub Mandrel
        Participant
          @submandrel

          Hi David,

          Gunmetal does not wear well on gunmetal. It wears best with a harder metal.

          In general avoid two similar metals moving against each other, the exception is cast iron.

          Neil

          25 August 2013 at 10:08 #127822
          JasonB
          Moderator
            @jasonb

            I'd probably opt for brass for both the piston and valve, keep the stainless for the rods

            25 August 2013 at 11:50 #127831
            MICHAEL WILLIAMS
            Participant
              @michaelwilliams41215

              Hi David ,

              A lot depends on what type of engine it is , how big it is and what running it will do .

              Tell us a little more if you want to and we’ll be able to give more definite answer.

              Regards ,

              MikeW

              25 August 2013 at 15:19 #127847
              david simmo
              Participant
                @davidsimmo

                hi mickw it a3 1/2 gauge brittania hopefully along time thanks dave

                Edited By david simmo on 25/08/2013 15:20:29

                25 August 2013 at 17:08 #127857
                Sub Mandrel
                Participant
                  @submandrel

                  So presumably piston valves. I'd suggest stainless steel, finished to as smooth and close a fit as you can get.

                  Neil

                  26 August 2013 at 19:18 #127930
                  MICHAEL WILLIAMS
                  Participant
                    @michaelwilliams41215

                    As Neil says stainless steel is a good option .

                    Other options include modern engineering plastics and properly ringed valve designs where the spool material itself matters less .

                    In smaller sizes piston valves often fail for secondary reasons like inadequate lubrication or by being unable to float freely on valve spindle .

                    Often said that there is no side load on piston valves therefore they don’t wear – this I’m afraid is untrue – there can be significant side loads if the whole valve drive system is not well thought out – worth a review of what the set up is in your engine .

                    Regards ,

                    MikeW

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