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Re: Valve end dimension

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  • gregsummerton
    Oops! It looks like the link might not work, just go to the Files section for this group please and look for: Valve end001.jpg Valve end002.jpg Greg
    Message 1 of 12 , Aug 1, 2009
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      Oops! It looks like the link might not work, just go to the "Files" section for this group please and look for:
      Valve end001.jpg
      Valve end002.jpg

      Greg
    • Eldert Rademaker
      Hi Greg i would not know but i do not like the split keepers you are using go to the Kibblewhite precision machining catalog
      Message 2 of 12 , Aug 1, 2009
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        Hi Greg
        i would not know but i do not like the split keepers you are using
        go to the Kibblewhite precision machining catalog

        http://www.blackdiamondvalves.com/products.htm

        and look up page 157 they list keepers there , i would go for the
        style 2 keepers .

        Eldert



        , "gregsummerton" wrote:
        >
        > I've been trying to work out what the minimum length of valve end I need above the collet groove in an engine I am building.


        > Thanks,
        > Greg
      • gregsummerton
        ... Utterly brilliant Eldert! Thanks, you ve saved me again! This afternoon I tryed to find the extra room I need by thinning the valve washer and cup fitted
        Message 3 of 12 , Aug 2, 2009
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          --- In mc-engine@yahoogroups.com, "Eldert Rademaker" <radducs@...> wrote:
          >
          > Hi Greg
          > i would not know but i do not like the split keepers you are using
          > go to the Kibblewhite precision machining catalog
          >
          > http://www.blackdiamondvalves.com/products.htm
          >
          > and look up page 157 they list keepers there , i would go for the
          > style 2 keepers .
          >
          > Eldert
          >

          Utterly brilliant Eldert!
          Thanks, you've saved me again!

          This afternoon I tryed to find the extra room I need by thinning the valve washer and cup fitted underneath the valve using AutoCAD ....but I did not really like the thin pieces that resulted, so I decided that a better solution to my problem would be to find some keepers exactly like the ones you have suggested.

          This will solve my problem, so that is enough I guess....but I'd still like to find out one day how to work out the correct proportion of the valve end to achieve the best reliability consistent with the shortest end.

          Thanks,
          Greg
        • Arthur Middleton
          ... Well, since no one jumped in, here s a non-expert opinion. The tip of the valve stem is loaded in shear by the spring pressure. Since a rocker or cam is
          Message 4 of 12 , Aug 2, 2009
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            > This will solve my problem, so that is enough I guess....but I'd
            > still like to find out one day how to work out the correct
            > proportion of the valve end to achieve the best reliability
            > consistent with the shortest end.
            >
            > Thanks,
            > Greg

            Well, since no one jumped in, here's a non-expert opinion. The tip of the
            valve stem is loaded in shear by the spring pressure. Since a rocker or cam
            is pressing on the tip during operation, the tip is supported at maximum
            spring compression, so I imagine the extended spring force (valve closed) is
            the max load condition.

            Thinning it doesn't change the cylindrical cross section but does reduce the
            vertical (in Greg's drawing), shear, section. The collet is taking the max
            spring force (fully open valve, max spring compression) so is subject to
            more stress. Assuming the collet lugs have the same shear strength as the
            valve stem (which they might well not) then matching the tip height with the
            groove width should be adequate. May need top allow something for wear, but
            that should be minimal. For safety, I suppose it's better that the collet
            lugs shear rather than the valve stem tip, so make it a bit thicker for
            safety.

            Any experts care to comment?

            Arthur.
          • Eldert Rademaker
            Hi Greg it doesnt matter what engine you work on we al run into the same problems . i use valves with 7 mm stems and use shortened Kawasaki keepers ( part nr
            Message 5 of 12 , Aug 2, 2009
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              Hi Greg
              it doesnt matter what engine you work on we al run into the same problems . i use valves with 7 mm stems and use shortened Kawasaki keepers ( part nr 12011 - 004 ) they are the style 2 keepers and i have to grind a little of the top

              the valve springs i use have a installed height of 32.5 mm and can handle 14 mm of lift

              Eldert

              "gregsummerton" wrote:

              Utterly brilliant Eldert!
              > Thanks, you've saved me again!
              >
              > This afternoon I tryed to find the extra room I need by thinning the valve washer and cup fitted underneath the valve using AutoCAD ....but I did not really like the thin pieces that resulted, so I decided that a better solution to my problem would be to find some keepers exactly like the ones you have suggested.
              >
              > This will solve my problem, so that is enough I guess....but I'd still like to find out one day how to work out the correct proportion of the valve end to achieve the best reliability consistent with the shortest end.
              >
              > Thanks,
              > Greg
            • gregsummerton
              ... Arthur, Do you mean matching the tip height with the groove width or do you mean matching it with the groove diameter? I ve drawn this up and just using
              Message 6 of 12 , Aug 2, 2009
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                Arthur wrote:

                > The tip of the valve stem is loaded in shear by the spring pressure. Since a rocker or cam
                > is pressing on the tip during operation, the tip is supported at maximum
                > spring compression, so I imagine the extended spring force (valve closed) is
                > the max load condition.
                >
                > Thinning it doesn't change the cylindrical cross section but does reduce the
                > vertical (in Greg's drawing), shear, section. The collet is taking the max
                > spring force (fully open valve, max spring compression) so is subject to
                > more stress. Assuming the collet lugs have the same shear strength as the
                > valve stem (which they might well not) then matching the tip height with the
                > groove width should be adequate.

                Arthur,
                Do you mean "matching the tip height with the groove width" or do you mean matching it with the groove diameter?

                I've drawn this up and just using intuition I feel that this is excessive, I am leaning towards matching it with half the diameter of the grooved section of the valve end.

                How did I arrive at this "intuitive" conclusion?
                If you draw, as I did, a cross section of the valve end and add a circle with a centre in the top 'corner' of the groove and give it a radius equal to the radius of the grooved section of the stem then you can see the cross section of material that has to shear or mushroom upwards for the top section of the valve to fail. It would appear that any additional length would contribute nothing.

                Also, I wonder if the maximum load on the valve tip and collets might come from the inertia of the mass of the valve spring collets/keepers, washers and the top section of the valve spring when the valve slams shut?
                I guess it depends on the cam design, revs and mass of these parts but I'd not be surprised if this inertial load is not larger than the spring load in a race engine....but I could be wrong.

                I guess the shear strength of the collets may be considerably less than the valve stem at the collet groove in most designs?
                "Racing quality" collets are usually made from a stronger material than the valve itself I guess so the cross sections are not a good guide to what will fail first.
                I lack the skills to calculate the actual dimensions of the groove, collet engagement and tip length so I have to go by "feel" ...and I guess many others do the same, even in the industry.

                My struggle for the room to fit the required valve springs, keepers etc when trying to gain extra performance from an existing design would be nothing new for many on this list.

                Thanks for your input, it's been a bit quiet on this one.
                Greg
              • Ian
                ... True, it has been. Wondering anyone s opinion on the 570 Husaberg upside down motor ? I was over at the start of the Australian Safari ( our mini-Dakar )
                Message 7 of 12 , Aug 2, 2009
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                  >Thanks for your input, it's been a bit quiet on this one.


                  True, it has been.

                  Wondering anyone's opinion on the 570 Husaberg upside down motor ?

                  I was over at the start of the Australian Safari ( our mini-Dakar ) and
                  the Berg team was well represented. I had a good look at the 570 Bergs
                  and was very impressed, I've always liked Berg's, their guys seem to
                  think outside the square.

                  OK - Bergs are prone to some problems, but that's the price of cutting
                  edge design.

                  Thoughts ?
                  _________________________________________________________

                  BTW - Safari Tanks ( Australia ) are now making long range tanks for
                  the 570's, not an easy job. ( Due to the EFI & frame set up )




                  Cheers IAN


                  See www.drysdalev8.com for :
                  - Drysdale 750-V8 Sports & 1000-V8 Cruiser
                  - DRYVTECH 2x2x2 Experimental
                  - Carberry Enfield 1000cc V-Twin
                  - Drysdale Hillclimb Open Wheeler
                • Julian Bond
                  Ian Mon, 3 Aug 2009 15:04:07 ... What are they doing with the balancer? Is it the same reverse spinning weight on the crankshaft? -- Julian Bond
                  Message 8 of 12 , Aug 2, 2009
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                    Ian <iwd@...> Mon, 3 Aug 2009 15:04:07
                    >Wondering anyone's opinion on the 570 Husaberg upside down motor ?
                    >
                    >I was over at the start of the Australian Safari ( our mini-Dakar ) and
                    >the Berg team was well represented. I had a good look at the 570 Bergs
                    >and was very impressed, I've always liked Berg's, their guys seem to
                    >think outside the square.

                    What are they doing with the balancer? Is it the same reverse spinning
                    weight on the crankshaft?

                    --
                    Julian Bond E&MSN: julian_bond at voidstar.com M: +44 (0)77 5907 2173
                    Webmaster: http://www.ecademy.com/ T: +44 (0)192 0412 433
                    Personal WebLog: http://www.voidstar.com/ skype:julian.bond?chat
                    Things I Hate: "Volvos"
                  • Arthur Middleton
                    ... I mean vertically measured (in your drawing) groove width. I don t see what the diameter has to do with the tip height. The cross section area in shear
                    Message 9 of 12 , Aug 3, 2009
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                      Greg wrote:
                      > Do you mean "matching the tip height with the groove width" or do
                      > you mean matching it with the groove diameter?
                      >
                      > I've drawn this up and just using intuition I feel that this is
                      > excessive, I am leaning towards matching it with half the
                      > diameter of the grooved section of the valve end.

                      I mean vertically measured (in your drawing) groove width. I don't see what
                      the diameter has to do with the tip height. The cross section area in shear
                      changes with circumference, as there is more material to shear if the
                      circumference is greater. The circumference is the smaller for the valve tip
                      than for the collet, as both seem likely to shear at the root. However, both
                      the diameter of the groove and of the collet are fixed (I presume).

                      > How did I arrive at this "intuitive" conclusion?
                      > If you draw, as I did, a cross section of the valve end and add a
                      > circle with a centre in the top 'corner' of the groove and give
                      > it a radius equal to the radius of the grooved section of the
                      > stem then you can see the cross section of material that has to
                      > shear or mushroom upwards for the top section of the valve to
                      > fail. It would appear that any additional length would contribute nothing.

                      I'm not sure what you are saying. I find a way to visualise what is
                      happening is to mentally reduce the parameter in question to near zero. If
                      the tip above the groove is, say, 0.001mm, what way does it fail?

                      > Also, I wonder if the maximum load on the valve tip and collets
                      > might come from the inertia of the mass of the valve spring
                      > collets/keepers, washers and the top section of the valve spring
                      > when the valve slams shut?
                      > I guess it depends on the cam design, revs and mass of these
                      > parts but I'd not be surprised if this inertial load is not
                      > larger than the spring load in a race engine....but I could be wrong.

                      I was thinking the same, that the max load may be at valve float where the
                      valve cannot close as fast as the cam moves and the valve slams shut. The
                      inertia of some of the valve/spring/collet will be additional to the spring
                      force. Perhaps this is (part of) what causes valve seat wear?

                      > I guess the shear strength of the collets may be considerably
                      > less than the valve stem at the collet groove in most designs?
                      > "Racing quality" collets are usually made from a stronger
                      > material than the valve itself I guess so the cross sections are
                      > not a good guide to what will fail first.
                      > I lack the skills to calculate the actual dimensions of the
                      > groove, collet engagement and tip length so I have to go by
                      > "feel" ...and I guess many others do the same, even in the industry.

                      I expect you're right in this, but I've no knowledge of commercial engine
                      development. Testing is probably needed anyway, even with FEA.

                      Arthur.
                    • Ian
                      ... Good question, I was interested in that too - no, they have ditched the beside crank balancer for a conventional gear driven one. ( To the relief of many
                      Message 10 of 12 , Aug 3, 2009
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                        >What are they doing with the balancer? Is it the same reverse spinning
                        >weight on the crankshaft?


                        Good question, I was interested in that too - no, they have ditched
                        the "beside crank" balancer for a conventional gear driven one.
                        ( To the relief of many Berg dealer workshop foreman I bet )



                        Cheers IAN


                        See www.drysdalev8.com for :
                        - Drysdale 750-V8 Sports & 1000-V8 Cruiser
                        - DRYVTECH 2x2x2 Experimental
                        - Carberry Enfield 1000cc V-Twin
                        - Drysdale Hillclimb Open Wheeler
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