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Motor Height

Thread in 'Nitro & Tracker Owners' started by Scott Ertelt, Jul 1, 2017.

  1. Scott Ertelt

    Scott Ertelt Member

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    Just finished up the break in period in my ZV18 boat, I have a Mercury Verado and was wondering if I could get some input here. I am thinking the motor mounted from the factory is maybe a bit low, the hole shot to plane is very good but at full throttle it is just getting to about 5950 rpms. red line is 6400 rpms on this motor. Being new to having a jack plate on the boat was wondering if things are set up differently than what I am familiar with.
    I figure lifting might get me up on rpms, and add to the speed but was looking for someone who has moved there's a bit and see what outcomes good or bad have been noticed.
    Thanks
     
  2. Rohu

    Rohu Moderator Staff Member

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    Honestly quite a few things will affect WOT rpm. The best way to check motor height is on a calm water period. Get on plane trimmed half way and have a passenger safely look back and see where the cavitation plate is positioned in the water. The ideal spot would be skimming across the water line. Below the water line it needs to be raised. Any higher than skimming across the water line needs to be lowered. There is no magic spot without doing this due to different props, the way the boat is loaded etc.
     
  3. Scott Ertelt

    Scott Ertelt Member

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    I did some testing and rigged up one of my underwater camera's to watch what was going on as I trimmed to different heights. I was getting a lot of splash coming up between the motor and boat and have raised it some but have not had a chance to try it out. Was the plan for today but we are having thunder storms now. I only had the manual jack plate, but it is was very easy to raise the motor. Just will take some playing around.
    Looks to me the prop that I have after speaking with Mercury would be the desired one. I think that factory install for the motor is very conservative, it gets you up on plane almost instantly will update when I get a bit more water time.
    Thanks For input.
     
  4. Scott Ertelt

    Scott Ertelt Member

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    I gained 1.9 mph. with raising the motor on jack plate 1/2" , the rpm. is at just a bit under 6,000 so after looking at what going on I will raise it another 1/2" inch and see if I break the 50mph. mark. I think its possible I have had full tank of gas and full live well on my tests, I think if I was half tank and no water in live wells I could hit 50 now, or very close. Last weekend with friends, we were just sight seeing more than anything with 4 people in the boat we can hit plane amazingly fast using half throttle or less. I am very impressed with that part after getting on plane it would stay on top down to about 15 mph before it starts dropping down into the water.
    Been keeping an eye on temps and water pressures and all are same as before it was raised. Will test it next week on Devils Lake and see what changes.
     
  5. Kirby Wilson

    Kirby Wilson Well-Known Member

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    Watch your roster tail. Running full out it should be around the same height as the motor. After you get the max performance out of the boat check the mid range operation. Had to lower a motor once by 0.25" due to prop slippage while operating in mid range. Dropped about a mile per hour at top range but worth the loss.
    Question; is the motor a 150 hp and the prop a 23 pitch? Also check the performance curve on that motor. It should be available on the Mercury web site. As long as you are in the performance rpm power range of the motor.
    Try raising the motor .25 inch when tweaking the performance.
     
  6. Paul sitko

    Paul sitko New Member

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    Yes I’m having the same problem you are
    I did move my jack plate up 3/4 of an inch and gained about 2 1/2 mph but the rpm stayed the same under 6000 I am trying to work with a local marina to try different props after talking to Jerry the mercuty marine specialist I met at a bass tournament I have the Enertia prop right now on boat
     
  7. CM17

    CM17 New Member

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    Same issue, 200 hp verado L4, nearing 30 hrs, after some reading I see most performance discussicussion state that the prop centerline to pad height should be between 3 1/2” to 4 1/2” .. looks like the factory setting on these zv18’s is about 6 1/2”! So from factory I was lucky to get 45mph, great hole shot but lousy top end, need to trim the motor almost into the ‘trailering range’ on the gauge to get any speed. Anyway, I have raised my motor now 2 3/4” and now get about 50mph out of it and need only trim it just above neutral (just over 1/2 way point of the trim gauge). The motor is reaching the 6400 rpm range now so I am going to switch the 18 pitch Enercia (factory) with a 19 pitch Enercia I have, hoping for a few more mph and to drop RPM to about 6200. Let me know what things you have tried and what results you are seeing as well please. A little disappointed in the speed of this boat and how much tweaking it’s taking to be perfectly honest.
     
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