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mercruiser 19 pitch 3800 rpm 28 mph 18 ft cuddy, do i need a 17 pitch?

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  • mercruiser 19 pitch 3800 rpm 28 mph 18 ft cuddy, do i need a 17 pitch?

    mercruiser 19 pitch 3800 rpm 28 mph 18 ft cuddy, do i need a 17 pitch? takes 30 seconds to plane out.

  • #2
    1980 mercruiser 120

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    • #3
      Is the engine in good mechanical condition, is it firing on all cylinders, carb opening fully, spark advancing? These are some of the things that need verification first.
      What is your outdrives gear ratio?
      Have you had this boat a while? If so, was it’s performance better in the past?

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      • #4
        also, what is the compression look like for each cylinder?
        Cheesehead boating the Gulf Coast of FLA 27.51° N, 82.53° W

        1988 Cruisers Rogue 2420 -VP 290 DP now powered by custom 468 - https://forums.iboats.com/forum/owner...988-rogue-2420

        Past Boats
        1970 Wooster Hellion - Merc 9.8
        2002 SeaRay 190BR - 5.0 - A1G2 - "Cheeseheads in Paradise"
        1984 Avanti 170DLI -3.0 stringer- "Ship Happens"

        What’s behind you doesn’t matter.Enzo Ferrari

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        • #5
          motor is strong! have wot. where do i find the gear ratio info? local marina say i need a 15p. project boat, first time in last night.

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          • #6
            boat weighs about 2600.

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            • #7
              The gear ratio info should be located on the Band on the upper gear case. Do you know what the WOT range for your engine is?

              EDIT:
              Your engines WOT rpm range is 3900 - 4300 rpm, the Gear ratio is supposed to be 1.98:1
              You are only 100 rpm below the bottom of the range, a 17 should bring it up to 4200. a 15 would be too little pitch and would have the engine over revving by 300 rpm. Proper trimming of load and of engine will probably bring it to 4300 with the 17
              Last edited by jimmbo; September 11th, 2019, 12:26 PM.

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              • #8
                I got rid of a 20 ft cuddy with a 140 in it... had a 15p 4 blade.. did the job fine, 4800 rpm, hit 30-32... using anything but a 4 blade on an underpowered heavy boat is folly
                "Na ise kalyteros anthropos apo ton patera sou"

                (greek= Be a better man than your father)....

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                • #9
                  Its a 1970's engine, from what i found the engine should turn 4500 -4600 wot. I wondered about the 4 blade prop, i will look into that, thanks guys for your help. I will check gear ratio tonight and let ya know, thanks again!

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                  • #10
                    In one post it is a 1980, now it's a 70s engine...

                    According to the Mercruiser Brochures, the WOT Range is 3900 - 4300
                    Last edited by jimmbo; September 11th, 2019, 02:05 PM.

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                    • #11
                      A lowchopr, you motor is either real tired and needs a rebuild, or you need a major tune up.

                      Do a compression test
                      94 Formula 27PC Custom 509MPI MEFI3 , B3 XR
                      95 Rinker 232 w/ 7.4L Carb 0F425011 B1 0F486471
                      07 Seadoo GTX
                      Merc Adults Only VP Adults Only
                      G-Dad always said "First Liar doesn't stand a chance"

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                      • #12
                        Hi
                        if it’s the old 2.5l 120 I think it is. I’m pretty sure the max is about 4300 maybe.
                        19” naturally sounds a bit much for her being a old heavy cuddy. For all we know she could be a little soggy bottomed after all these years.
                        Be lovely if you could keep her healthy and original together.
                        I would maybe be at a good 17” black max ally prop and see how she goes, giving the old girl every chance and running light as you can manage every outing.
                        These old girls need tender care and respect really.

                        Ive an old glastron CVX16 Classic with a 150 v6 merc 2 stroke. Although I and others would love to see what she will manage wot and propped well...and I love a bit of speed and all that. Part of me can’t help but maybe give her an easy time of it. She’s nearly 40 year old and so is the transom too, obviously. The power of the big merc will no doubt have her at ridiculous pace...but is it worth risking the transom for ?? Maybe haha. Maybe not. Ok...just once...Ill let you know how it goes.
                        In the mean time. Go easy on your old girl. Fire a 17” black max on her and all will be well.

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                        • #13
                          all i know is the engine is pre 85, sorry i dont know the exact year. i looked all over that out drive and i cant see where the gear ratio is located, is that 17 black max a 4 blade prop?. im pretty sure its not waterlogged i had it weighed at the local grain mill, came out to 2500 lbs with gear in it. local marina has a 17p used,,, I'm going to try that this sunday...i need to stress that the engine is running perfectly, it does not need a compression test. i have a video on you tube of our test run 2 nights ago, shows the boat taking off at full throttle, check it out! just type in "eric and denny on pleasant hill lake 2" should pop right up , thanks again!!
                          Last edited by Lowchopr; September 12th, 2019, 08:34 AM.

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                          • #14
                            heres a link as well https://www.youtube.com/watch?v=irhAIzKLm54

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                            • #15
                              Sign up today
                              All motors can run perfect and still be low on power from wear.
                              Example: new 200hp motor with 150 psi per cylinder, over time can go to 100 psi and still run great, but not have all the power it once did

                              The 17 may be all you need
                              94 Formula 27PC Custom 509MPI MEFI3 , B3 XR
                              95 Rinker 232 w/ 7.4L Carb 0F425011 B1 0F486471
                              07 Seadoo GTX
                              Merc Adults Only VP Adults Only
                              G-Dad always said "First Liar doesn't stand a chance"

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