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.
      Small town S. W. Ga./St. James Fl.

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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
        [email protected]
        941-735-5808

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        • #5
          Click image for larger version

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          Ken Reeves
          [email protected]m
          941-735-5808

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          • #6
            hope that is big enough to read.

            Ken Reeves
            [email protected]
            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

              [email protected]
              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
                  [email protected]
                  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
                        [email protected]
                        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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                          • #14
                            Ken - Update. After the proper break-in time etc. I am getting the following stats:

                            Max RPM 5600 - 56 MPH (Just me on the boat, with some trim)

                            Cruise RPM 4200 - 42 MPH

                            Max RPM 5400 - 51 MPH (boat is loaded with 10 plus people and a lot of coolers, etc).

                            I am worried that I am over propped?

                            Since my boat does not like a lot of trim (it porpoises a lot), I am thinking a 19P Rev4 would be best?

                            Whats your thoughts?

                            Also, what do you recommend for Hubs? I think I need a new set.

                            Thanks

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                            • #15
                              Strange that you only gained 1 MPH with a 100 HP gain.

                              19's should do ok.
                              I'd go Quicksilver Q4's (same exact prop, but $70 less) most of that 70 is for a Mercury hub kit that comes with the Rev 4 that your not going to use anyways.
                              As for hub kits, I'd suggest the Solas 203 hubs. They will shift a lot softer then the Quicksilver hubs.

                              Ken Reeves
                              [email protected]
                              941-735-5808

                              Comment

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