Announcement

Collapse
No announcement yet.

Engine Rotation

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

    Engine Rotation

    We have an older 1988 Bayliner 2560 and are wanting to install a crate GM 5.7 engine. The boat has the infamous OMC outdrive. I am wanting to know whether I should order reverse or forward engine.
    Post suggest that it will most likely be a reverse. Input?

    #2
    order a "standard" left hand rotation engine.... unless you want to change the rotation of the outdrive or use a counter rotating prop....

    cobra or stringer? the Infamous OMC cobra outdrive is a good long life drive if set up correctly.... yes, there are others that are more efficient, and newer, but the OMC will get you there and back many times without worry IF you get the shift cables adjusted as required, which was seldom done until they realized what the problem was with them... and STILL, some owners dont know the importance of this procedure.
    and there are still plenty of parts available for them....

    EDIT; a right hand rotating engine is considered a counter rotating engine, because it turns counter to the standard left hand rotating engine, as standing behind the rear of the engine looking forward....


    NU LIBERTE'
    Salem, OR

    1989 Bayliner 2556 Convertible
    5.7 OMC Cobra - 15.5x11 prop
    N2K equipped throughout..
    2014 Ram 3500 crew cab, 6.7 Cummins
    2007 M-3705 SLC weekend warrior, 5th wheel
    '04 Polaris Sportsman 700 -- '05 Polaris Sportsman 500 HO
    Heavy Equipment Repair and Specialty Welding

    Comment


    • SCL
      SCL commented
      Editing a comment
      Thanks so much. We have the OMC Cobra .

    #3
    As Centerline said, you will want a standard left hand rotation engine, and you’ll want the Marine build!
    Your OMC Cobra outdrive is not designed to work with a reverse right hand rotation engine.
    Rick E. Gresham, Oregon
    2850 Bounty Sedan Flybridge model
    Twin 280 HP 5.7's w/ Closed Cooling
    Volvo Penta DuoProp Drives
    Kohler 4 CZ Gen Set

    Comment


    • Gsherwood
      Gsherwood commented
      Editing a comment
      Is that because of the transmission? Can the engine run in either direction?

    • SCL
      SCL commented
      Editing a comment
      Really appreciate you helping with getting this boat back in the water

    #4
    ................
    Originally posted by Gsherwood
    Is that because of the transmission?
    The OMC Cobra upper gear set is designed to operate in one direction only..... i.e., behind a standard LH engine rotation.

    The lower gear set is also designed to operate the propeller in the FWD gear in one direction only.


    Can the engine run in either direction?
    Not without major internal changes..... i.e., camshaft, piston wrist pin offset, crankshaft seals, etc.

    In order to run a REV RH Rotation engine with a stern drive behind it, the drive would need to be a special unit.
    To the best of my knowledge, OMC never offered one for a REV RH engine!

    However, the Volvo Penta s/p stern drives are ambidextrous (regarding propeller rotation) but still require a Std LH rotation engine.
    This has been designed into the Cone Clutch transmission gears/bearings, and into the lower gear unit "drive" and "driven" gears/bearings.


    Bottom line..... your new Marine Engine needs to be a Std LH Rotation engine and it should be a Marine Build.... not an automotive build!




    By the way.......engine rotation is always viewed as though looking at the flywheel end!


    Rick E. Gresham, Oregon
    2850 Bounty Sedan Flybridge model
    Twin 280 HP 5.7's w/ Closed Cooling
    Volvo Penta DuoProp Drives
    Kohler 4 CZ Gen Set

    Comment


      #5
      I guess some marine parts shops make it confusing. When I put my data in (year, omc, cobra, 5.8) they always ask if it is a left or right turning engine. That leads me to believe there are right hand turning engines and drives.

      Comment


        #6
        Originally posted by Metrodriver View Post
        I guess some marine parts shops make it confusing. When I put my data in (year, omc, cobra, 5.8) they always ask if it is a left or right turning engine. That leads me to believe there are right hand turning engines and drives.
        OMC did build some reverse rotation Cobra legs for dual drive boats, the internals of the "bullet" is where the difference is.
        " WET EVER "
        1989 2459 TROPHY OFFSHORE 5.8L COBRA / SX
        mmsi 338108404
        mmsi 338124956
        "I started with nothing and still have most of it left"

        Comment


          #7
          Just to clarify a few things:

          The supplier who asked you about the rotation may have been thinking about In-Boards. In-Board boats (from years past) would use both a Std LH Rotation engine and a REV RH Rotation engine.
          Some of the In Board transmissions would run in either direction with a change to the transmission's oil pump rotation.
          This allowed them to work with a REV RH rotation engine.

          Then we'll see twin Std LH Rotation engines used with transmissions that are "opposite of engine rotation" capable.
          This allows the use of two Std LH Rotation engine, yet they spin the props in different directions.

          As for stern drives, I think that you'd need to go back to the Merc TRS drives to find a REV RH Rotation engine used in front of one.

          As for the OMC Engines using an opposite rotation stern drive, the opposing rotation refers to the propeller, not the engine.
          In this scenario, both engines are Std LH Rotation.


          Here is what we will see as a typical and correct twin engine propeller rotation.





          As shown in the left side image, the "counter-rotation" applies to the propeller, not the engine, although the Std LH engine will also rotate as shown.

          The image on the right side would apply to a single engine boat with either the OMC or Merc Dog Clutch drives.
          While the engine may be a Std LH Rotation, the use of a RH prop is due to the lower gear unit gear design regarding the FWD propulsion gear and it's thrust bearing location.




          .
          Rick E. Gresham, Oregon
          2850 Bounty Sedan Flybridge model
          Twin 280 HP 5.7's w/ Closed Cooling
          Volvo Penta DuoProp Drives
          Kohler 4 CZ Gen Set

          Comment


            #8
            These are the 2 variations I find on Crowley marine and a few others. My engine turns left (looking from behind the engine at the flywheel) and my prop turns right (I believe, can't confirm it right now). It has powersteering.
            What engine model number would be correct?

            Comment


            • Centerline2
              Centerline2 commented
              Editing a comment
              That is the normal setup...

            #9
            Originally posted by Metrodriver View Post
            These are the 2 variations I find on Crowley marine and a few others. My engine turns left (looking from behind the engine at the flywheel) and my prop turns right (I believe, can't confirm it right now). It has powersteering.
            What engine model number would be correct?
            I can’t tell you what the engine model number would be, but I can tell you that you will need a Standard LH rotation engine.



            Rick E. Gresham, Oregon
            2850 Bounty Sedan Flybridge model
            Twin 280 HP 5.7's w/ Closed Cooling
            Volvo Penta DuoProp Drives
            Kohler 4 CZ Gen Set

            Comment


              #10
              I do have a left turning engine, but as you can see with powersteering it leads you to a right-turning engine model number. Where it confused the hell out of me was when I had to find the pn for the powersteering and alternator belts. Other parts were the same, or omni-directional like the water circulating pump.

              Comment


                #11
                Originally posted by Metrodriver View Post
                These are the 2 variations I find on Crowley marine and a few others. My engine turns left (looking from behind the engine at the flywheel) and my prop turns right (I believe, can't confirm it right now). It has powersteering.
                What engine model number would be correct?
                You have the 2nd one, with the R in the number.
                Those model numbers refer only the the outdrive, you have a Right turning prop and a standard Left turning engine.
                " WET EVER "
                1989 2459 TROPHY OFFSHORE 5.8L COBRA / SX
                mmsi 338108404
                mmsi 338124956
                "I started with nothing and still have most of it left"

                Comment


                  #12
                  Thanks for clarifying that. I have been looking at the wrong model.....

                  Comment

                  Working...
                  X