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  1. #11
    Duke's Avatar
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    Part 3

    Also take note that when bending a DF for the GPR the outside diameter grows as you increase pitch.

    You can carefully file or grind the outside of the prop while setting it squarely down on the liner marking the stop point each time. Jim's Performance can cut the OD for you also. Small tweeks back and forth don't usually require much fitment after the initial cut.

    I believe .015 total clearence with prop loose in liner is ideal. .007 to .008 all the way around if bolted together. If running Carl's PVC insert it can be much tighter. Someone please correct if this is wrong.


  2. #12
    My son (mohawk man) jeffsntx's Avatar
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    Quote Originally Posted by Duke View Post
    Also take note that when bending a DF for the GPR the outside diameter grows as you increase pitch.

    You can carefully file or grind the outside of the prop while setting it squarely down on the liner marking the stop point each time. Jim's Performance can cut the OD for you also. Small tweeks back and forth don't usually require much fitment after the initial cut.

    I believe .015 total clearence with prop loose in liner is ideal. .007 to .008 all the way around if bolted together. If running Carl's PVC insert it can be much tighter. Someone please correct if this is wrong.

    Duke, I am having a problem with my ski turning WAY too many RPM's with the 14/20 Dynafly and the plastic liner I bought from Carl. I am going to pull the complete assembly apart tonight and see whats going on. I was under the assumption that the plastic wear ring would have to be "burned in" to the new prop. When I assembled the pump it just slid right in, so I am going to check clearances tonight and i will let yall know.

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  4. #13
    Happily Self-Employed WFO's Avatar
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    Good stuff Duke. I like that flat plate idea.

    Very true about the outer diameter on the Dynafly. IMO do not try to cut it yourself, or even bend it unless you know and are confident in what you are doing. Jim does cut them, but so does Carl @ Island Racing, Erick @ Speedfreeks, Dave @ Impros, and any other actuall prop shops.

  5. #14
    Duke's Avatar
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    Quote Originally Posted by WFO View Post
    Good stuff Duke. I like that flat plate idea.

    Very true about the outer diameter on the Dynafly. IMO do not try to cut it yourself, or even bend it unless you know and are confident in what you are doing. Jim does cut them, but so does Carl @ Island Racing, Erick @ Speedfreeks, Dave @ Impros, and any other actuall prop shops.

    Those are great shops too! I often but unintentionaly overlook them because Jim is so close to my location.

    Just trying to help out the diehard do it yourselfers like me.

  6. #15
    Chine Walker
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    Duke:
    I found the Watcon unit; how do you contact Tommy for his version?
    j.p.

  7. #16
    MR. SCOVILLE UNIT SUCKMYWAKE's Avatar
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    On the leading edge of the blade, measure 2 inches from the tip of blade. put a mark on each blade with a felt tip pen, on the edge of blade then set prop inside the pitch gauge. line up mark with blue lines on gauge find the line that best matches fom the mark back to the tip of blade most props are usualy a 13 or 14 . On the trailing edge of blade measure from tip back up blade 2 inches and mark each blade then put prop in gauge and line up mark with red lines find the line that matches from mark to tip on end of blade usualy 19 or 20 . when the correct pitch is matched to gauge the blade will be hidden by the mark. Try moving same prop blade to diffrent lings and you will see how the blade is no longer hidden by the line on the gauge. you are only measuring the first 2 inches of blade or the last 2 inches of blade as the middle of blade is the transition section of blade which you can't change.. a 14/20 prop usualy checks 13/19+ Notice how all blades don,t match the same pitch from one to the other Poor Quality control . The last 2 inches of the trailing blade is what you bend to change rpm's Higher pitch # reduces rpm's lower pitch # increases rpm's A '1' increase in prop pitch trailing end of blade usualy changes 75-100 rpm"s Leading edge pitch changes usualy has to to with acceleration only not max rpm's The lower the # on the leading edge the better acceleration I usualy run a 13 most of the time and change the trailing end to match my desired rpm's I like 7150-7250 on a single pipe ski.
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    does this explain things fella's????


  8. #17
    My son (mohawk man) jeffsntx's Avatar
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    Quote Originally Posted by jeffsntx View Post
    Duke, I am having a problem with my ski turning WAY too many RPM's with the 14/20 Dynafly and the plastic liner I bought from Carl. I am going to pull the complete assembly apart tonight and see whats going on. I was under the assumption that the plastic wear ring would have to be "burned in" to the new prop. When I assembled the pump it just slid right in, so I am going to check clearances tonight and i will let yall know.

    OK, I pulled the pump out of my ski last night. The clearances are right on the money (.007). I guess I will move to the next thing until I figure out why the ski is turning so many RPM's with the Dynafly with what I think is a low MPH.

  9. #18
    Duke's Avatar
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    Quote Originally Posted by jeffsntx View Post
    OK, I pulled the pump out of my ski last night. The clearances are right on the money (.007). I guess I will move to the next thing until I figure out why the ski is turning so many RPM's with the Dynafly with what I think is a low MPH.

    Good clearence Jeff. Are there any cavitation marks on the blades? Maybe an airleak at the wear ring or 2" spacer?

  10. #19
    My son (mohawk man) jeffsntx's Avatar
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    Duke, I am not running the 2" spacer and the prop doesnt even have an hour on it, no marks what so ever on it.

  11. #20
    Duke's Avatar
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    Quote Originally Posted by jpa1300 View Post
    Duke:
    I found the Watcon unit; how do you contact Tommy for his version?
    j.p.

    PM Tommy- 2fast4u is his forum name.

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