Thread: Vent ports?

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  1. 10-02-2020, 09:01 PM #1
    Blue76
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    Vent ports?

    I bought a RX4 15-20 prop from a board member. Trying to get out of the hole a little better. Current prop is a RakerII 14.5x22. Boat is a ranger 188dvx with a Etec 150.

    With the raker I was sluggish out of the hole in the summer but ok in the winter. With a load it sucked year around. Top speed was 56-58 on a good day. RPMs under 5000

    I put the RX4 On today. Water temps around 70ish. Same jack plate setting. Out of the hole it seems slightly better but not as good as I hoped. But, once it starts to get on plane it really accelerates much quicker. Once on plane the throttle response is noticeably better and it seems to take rough water a little better meaning it doesn’t lose speed as easily and it corners better. Top speed is down a couple MPH. RPMs are a tick over 5000. Gauge if accurate says 5100. Not worried about top speed. I am slower than everyone anyway.

    So... back to the subject line.... what do those vent ports do? I read something about the hole shot but have no idea what the procedure is for adjusting them.

    Greg
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  2. 21XDC
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    #2 10-03-2020, 05:24 AM
    This is the concept...


    Marks Props 317-398-9294, 1850 East 225 South, Shelbyville, Indiana 46176 propellerman59@gmail.com http://www.marksprops.com/index.html
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  3. greg88
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    #3 10-03-2020, 02:07 PM
    If your tach is correct you are way down on rpm I would double check that.
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  4. Blue76
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    #4 10-03-2020, 02:12 PM
    How does one check a tach? I have been told that before. R
    With this prop it is turning the highest RPM It ever has.
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  5. Almag6
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    #5 10-04-2020, 05:56 PM
    $10 tiny tach from ebay
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  6. Blue76
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    #6 10-07-2020, 04:48 PM
    I opened the vent ports yesterday about halfway. It helped the hole shot a lot. Opened them up about 3/4 today and it now just on plane like I had hoped for. Made my little 150 feel like it gained 50HP.

    Haven’t tested the tach but the highest RPM reading I got today was 5200 and 54.4 mph.
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