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  1. #1

    Installing 13/20 Prop (Help)

    I bought a used riva prop from a guy on Facebook gp1800 forums..

    Prop is in great condition, all he sent was nose cone and prop.

    Had to order the driveshaft tool and the impeller tool. They sent the wrong impeller tool. Has a ďAĒ in the part number even tho I ordered the other one. Itís way too big.

    The nose cone is also way too big. I was told itís actually faster to run without the nose cone? Is that true? Iím new to this stuff and my friend is installing for me so what do u guys recommend?

  2. #2
    BLASTER 1's Avatar
    Join Date
    Jul 2015
    I always thought it was better to have the cone installed, being its a much smoother transition. But I read a post from the greenhulk himself saying to ditch the cone so the next time I had my pump out I removed it to give it a try.
    Verdict::: I personally couldnít tell the difference if it was in or out so Iíve just left it out
    Good Luck with your install

  3. #3
    xkon's Avatar
    Join Date
    Jun 2017

    Recommended to leave it out. With that being said tho, I'm not sure why the manufacturers include them if there is no benefit?

  4. #4
    Super Jim's Avatar
    Join Date
    Feb 2007
    Lake Wylie, SC
    I would like to see a back to back test with and without the impeller nose cone. Don't say it.....I know I can do it if I really want to see it bad enough.

    My "guess" is it make very little difference in top speed. I know Greenhulk says it was proven "back in the day" that they there were "a little faster" without the nose cone. But who has the data? What was "a little), what ski? A lot of design changes have occurred since "back in day" I know in the late 90's I left nose cones out simply because they often did not stay in the impeller and walked up the drive shaft causing problems. Looking at the design, you would think the water flow would have to be better with the cone installed (maybe less cavitation ?).

    If anyone gets bored and has more motivation than me to pull the pump to perform a before and after test, many would love to see the results.

    I did not have the nose cone on my 13/20 but had intended to put it in with my 13/18 but forgot to do it so I'm still running with no nose cone.

  5. #5

    Join Date
    Jun 2017
    Ocean City, MD
    I run it. If anything it will keep dirt and water away from the threads. Pack grease or anti seize in the impeller and do not kill the set screws. I doubt there is a measurable difference.


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