F300 Props - Rev4's?

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  • F300 Props - Rev4's?

    I am replacing my current F250's for a new pair of F300's. I will be following the break-in recommendations per Yamaha. I am currently running Merc Rev4 - 20 pitch (great prop - only used it a few times before the end of the season). I am currently getting around 5800 - 6000 RPM's with my 250's.

    Looking to see if anyone could recommend the right pitch prop for my new 300's? Is my current set of Rev 4 - 20P under pitched?

    I also heard the F300 have / had a seal issues when running the Rev4's. I think this has been fixed?

    I am running a 35 Jefferson Marlago (twins).

    Thanks in advance.

  • #2
    I'm quite certain Ken will jump in, but here's my first hand experience: my Cobia 256 had an F300 manufactured in 2014 and of course, we blew the seal on the lower unit after we added a Rev4. It was only then that I found out about the whole F300/Rev4 issue.

    This happened in 2016 and I was told that newer F300s had a different, more durable seal and could now handle the Rev4. My fix included this newer seal. Regardless, I switched to a Powertech OFX4.

    My understanding is F300s manufactured after a certain date can handle the Rev4. Again, if Ken sees this thread, I'm sure he'll be able to supply more specific details.

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    • #3
      Ken really monitors the performance section regularly. Might want and put it down there.

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      • #4
        Here is the service bulletin.
        if the motors are 2014 or newer, you should be fine.

        What GPS speed were you getting with your 20 Rev 4's at 5800-6000 RPM?
        from that, we can figure out what speed to expect from the 300's and what RPM you'll turn.
        good chance they will run well on the 300's.


        Ken Reeves
        KR@Propgods.com
        941-735-5808

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        • #5
          Click image for larger version

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Name:	Yamaha seal 2.jpg
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          Ken Reeves
          KR@Propgods.com
          941-735-5808

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          • #6
            hope that is big enough to read.

            Ken Reeves
            KR@Propgods.com
            941-735-5808

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            • #7
              Originally posted by ken2 View Post
              hope that is big enough to read.
              Just click on it, it opens up.
              Engine Sales and Service
              Ph +1 954.463.1515
              Fx +1
              954.463.4904
              Toll Free: 800.622.6747

              oparker@parkeryacht.com
              www.parkeryacht.com

              Member of the MSHS Group

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              • #8
                Originally posted by ken2 View Post
                Here is the service bulletin.
                if the motors are 2014 or newer, you should be fine.

                What GPS speed were you getting with your 20 Rev 4's at 5800-6000 RPM?
                from that, we can figure out what speed to expect from the 300's and what RPM you'll turn.
                good chance they will run well on the 300's.
                Ken - I was getting around 50 - 54 MPH on the GPS. That was on my 2007 F250's TLR's.

                What are your thoughts?

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                • #9
                  Ok, I'll say 6000 at 53 is 7% slip

                  If 500 HP ran 53, 600 HP should run 58

                  58 MPH, 7% slip, 1.75 gear ratio would give 5730 RPM at 58 MPH with your 20 pitch Rev 4's. (My guess)

                  So I'd give them a run and see what happens. you might want to drop to 19's, just have to see how the numbers end up.

                  Ken Reeves
                  KR@Propgods.com
                  941-735-5808

                  Comment


                  • #10
                    Originally posted by ken2 View Post
                    Ok, I'll say 6000 at 53 is 7% slip

                    If 500 HP ran 53, 600 HP should run 58

                    58 MPH, 7% slip, 1.75 gear ratio would give 5730 RPM at 58 MPH with your 20 pitch Rev 4's. (My guess)

                    So I'd give them a run and see what happens. you might want to drop to 19's, just have to see how the numbers end up.
                    Ken - Thank you. I agree...I will try it out for the first 2 hours (per the break-in period)....if I can not make it out at 6000...I would look to downsize to a 19P.

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                    • #11
                      Originally posted by BOA3T View Post

                      Ken - Thank you. I agree...I will try it out for the first 2 hours (per the break-in period)....if I can not make it out at 6000...I would look to downsize to a 19P.
                      Ken - Please note my 250's where from 2007 and where the old gear ratio? Please advise...would that change your calculation?

                      Thanks

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                      • #12
                        Yes, my numbers are based on your old motors having 2.0 gear ratio, and new ones having 1.75.
                        (that is why your probably going to get lower RPM with your new motors, even though your going to go faster)

                        You don't absolutely have to hit 6000 RPM with the new ones.
                        if your at 5800, I'd say your fine.
                        but lets see what happens first.

                        Ken Reeves
                        KR@Propgods.com
                        941-735-5808

                        Comment


                        • #13
                          Originally posted by ken2 View Post
                          Yes, my numbers are based on your old motors having 2.0 gear ratio, and new ones having 1.75.
                          (that is why your probably going to get lower RPM with your new motors, even though your going to go faster)

                          You don't absolutely have to hit 6000 RPM with the new ones.
                          if your at 5800, I'd say your fine.
                          but lets see what happens first.
                          Ken - Thank you again for your help and time.

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