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1991 cone clutch king cobra transom hole

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  • 1991 cone clutch king cobra transom hole

    I am new here. Have read a lot of the posts and can not find a definite answer. I have a 1991 235 vista four Winn’s with the 5.7 king cobra cone clutch drive. I am in need of information about the transom cutout. I am looking to the future of replacing the lower unit with something. Are the mercruiser alpha and bravo and Volvo sx cutouts the same as the cone clutch omc? And what drives if any will work on the cone clutch transom Mount?

  • #2
    The answer to question # 2 is nothing will work on the Cone Clutch transom mount unfortunately. Its not like the standard Cobra where you could replace the pivot housing with the Volvo Penta part and then bolt up an SX drive. The answer to question #1 is I am not sure but part of the whole Cobra project was to use the same cut out as Merc to make OMC drives appeal to more boat companies that would not require different cut outs as the old Stringer and Volvo AQ drives did...you will have to check...
    After you determine if its the same cut out your best plan is to buy a donor boat and get the major parts (engine, transom mount, tilt n trim, power steering and the drive) all in one package. Buying it piecemeal will cost more than the project will ever be worth. Make sure the boat you have is in good enough shape to make this worth while (ie no stringer, deck or transom mount).
    1988 Four Winns 200 Horizon
    4.3 OMC Cobra

    98 Jeep Grand Cherokee 4.0 Selectrac
    07 Jeep Grand Cherokee Limited 5.7 Quadradrive II

    "While air doesn't freeze....rust never sleeps"

    Comment


    • #3
      Originally posted by Fourwinns235 View Post
      Are the mercruiser alpha and bravo and Volvo sx cutouts the same as the cone clutch omc?
      Howdy,

      Welcome aboard!

      Yes indeed. The Mercruiser and Volvo gimbal/transom mounts will bolt right in. You will have to drill 2 additional holes if you want to use a Bravo transom though.

      In 2006 I removed all the (1987) OMC 460 King Kobra "Stuff" from my Four Winns 211 Liberator and replaced with 1997 Mercruiser 7.4L Bravo III "Stuff"

      In a boat the size of yours, I would do the same. (454/502/496 with a Bravo III)

      In mine, while the HP was similar between the 460 and 454, (the 460 actually had 10hp more crankshaft hp)........

      The difference between the single prop Cobra and the twin prop contra-rotating Bravo III was nothing short of SPECTACULAR!! (especially the hole-shot!.....although it's probably about 3-5 mph slower....It did do 60mph with the Cobra, but was a real dog outta the hole!)

      You would see similar performance with a BBC + Volvo DUO-Prop.

      I originally tried to find a Volvo BB-Duoprop Package and found nothing used in the NW. Over a 6-mo period I found several Bravo I, II, III SBC/BBC packages (Mercruiser stuff is simply MORE available on the used market)

      I settled on a 1997 7.4/Bravo III out of a "totaled" 1998 24ft Cuddy Bayliner that had a tree fall across the bow. After buying it, I found a much newer 496 (425hp) EFI Bravo III for about $3500 more (wish I had bought it too!.....I could have "made money" on the 97 stuff" because I got it so cheap!!)

      I would suggest finding a 496 (375-425hp) EFI Bravo III because of the EFI, additional HP, closed cooling and "Dry-Joint" manifolds and risers.

      You'll LOVE the additional HP and performance.


      Cheers,


      Rick




      1987 FourWinns 211 Liberator, Originally an OMC 460 King Cobra.
      Re-powered in 2006 with a 1997 Mercruiser 7.4L Bravo III

      Comment


      • #4
        Originally posted by Lou C View Post
        The answer to question # 2 is nothing will work on the Cone Clutch transom mount unfortunately. Its not like the standard Cobra where you could replace the pivot housing with the Volvo Penta part and then bolt up an SX drive. The answer to question #1 is I am not sure but part of the whole Cobra project was to use the same cut out as Merc to make OMC drives appeal to more boat companies that would not require different cut outs as the old Stringer and Volvo AQ drives did...you will have to check...
        After you determine if its the same cut out your best plan is to buy a donor boat and get the major parts (engine, transom mount, tilt n trim, power steering and the drive) all in one package. Buying it piecemeal will cost more than the project will ever be worth. Make sure the boat you have is in good enough shape to make this worth while (ie no stringer, deck or transom mount).
        Lou, you ever seen a bolt on cast aluminum adapter? I've seen pictures of them, but never touched one.

        Comment


        • #5
          There was an adapter made to bolt a Merc onto a Volvo Penta AQ sized transom cut out, I don't now if they are still available but that would allow someone to convert a boat originally equipped with the AQ drive to the Merc without having to do a transom rebuild.
          The FW in question most likely has the standard sized cut out that will take an OMC, Merc or Volvo SX (not AQ).
          If he had the standard Cobra (dog clutch) that can be converted to a Volvo SX by changing the pivot housing to the one used on the SX. The rest of the Cobra transom mount is nearly identical to (but not exactly so) the SX design, because Volvo bought into OMC's sterndrive division (50%) and got the rights to use their transom design. They wanted this because the cut out was the same as Merc. However, what the OP has (OMC Cone Clutch) was designed and built before the joint venture with Volvo (these came on line around 1990, joint venture happened in 1994) and there is nothing else that will adapt to that transom mount. The cut out is the same but nothing about it is compared to the regular Cobra. Of course you'd have to do this with used parts, not OE prices from Volvo. So basically you remove the OMC pivot housing (the part the drive bolts onto with the 6 studs), add a Volvo or Johnson style engine mounted impeller pump and a Volvo SX or SX/DP drive in the correct ratio for your engine. If the parts can be bought used at the right price you can get the whole Volvo transom mount, inner and outer and in the OP's case that's what he'd have to do. Merc parts will be easier and cheaper to find.
          1988 Four Winns 200 Horizon
          4.3 OMC Cobra

          98 Jeep Grand Cherokee 4.0 Selectrac
          07 Jeep Grand Cherokee Limited 5.7 Quadradrive II

          "While air doesn't freeze....rust never sleeps"

          Comment


          • #6
            Originally posted by Lou C View Post
            what the OP has (OMC Cone Clutch) was designed and built before the joint venture with Volvo (these came on line around 1990, joint venture happened in 1994) and there is nothing else that will adapt to that transom mount. .........................Merc parts will be easier and cheaper to find.
            Yeah, I was under the impression that the "Interim" OMC (Cobra) drives and transoms were not similar to either the Dog or the SX.

            I even considered new (or nearly new) Volvo and Mercruiser. In that case, they were similar (to each other) in price. in 2006 about $24k (NOT-installed) in round numbers for either.

            Used, anything Volvo seemed more money if you can find it.

            Best way of course, is to find a similar sized damaged boat with everything already there and swap it over.



            1987 FourWinns 211 Liberator, Originally an OMC 460 King Cobra.
            Re-powered in 2006 with a 1997 Mercruiser 7.4L Bravo III

            Comment


            • #7
              Thank you for the answers. I’m not looking to make this boat any faster just make it go. It has a top speed of 32 mph on the god. What I am trying to find out is if this unit fails can I put in an alpha setup in the same transom without modifications. The water here in Michigan is hard as a rock right now and doner boats are cheap. I can buy a whole boat with an alpha and and bad 350 engine practically for free. After I sell the trailer. My engine is perfectly fine.

              Comment


              • #8
                I agree with Rick a Bravo drive would be what that boat should have. An Alpha will work but is limited to about 300 hp if you ever wanted to drop in a more powerful engine. If not the Alpha will suffice. The Volvo SX is the equal of the Bravo strength wise.
                1988 Four Winns 200 Horizon
                4.3 OMC Cobra

                98 Jeep Grand Cherokee 4.0 Selectrac
                07 Jeep Grand Cherokee Limited 5.7 Quadradrive II

                "While air doesn't freeze....rust never sleeps"

                Comment


                • #9
                  I have done a bunch of research and found that between the cone clutch and the regular cobra everything on the inside of the boat is the same. Even down to the four cylinder. My new plan is to purchase a regular cobra transom mount and a sei adaptor and mount a mercruiser alpha gen 2. There is a prop shop that has one ready to go dirt cheap. I will have to plug the top two transom mount holes. I have been told that is the only difference in the transom cutout. I know everyone here is looking to add more power and go faster but my little cruiser is just that, a cruiser that only goes out for island hopping 4 to 5 times a year.

                  Comment


                  • #10
                    Sign up today
                    Originally posted by Fourwinns235 View Post
                    My new plan is to purchase a regular cobra transom mount and a sei adaptor and mount a mercruiser alpha gen 2. There is a prop shop that has one ready to go dirt cheap. I will have to plug the top two transom mount holes. I have been told that is the only difference in the transom cutout. I know everyone here is looking to add more power and go faster but my little cruiser is just that, a cruiser that only goes out for island hopping 4 to 5 times a year.
                    That's a pretty good plan going to an SEI drive and Alpha GEN-II setup! When I replaced my King Kobra with a Bravo III I was pretty concerned with the "Fit"

                    Also, you might consider finding an Alpha GEN-II transom + other Mercury stuff to swap over to your basic long block engine. That would make the boat a little more sell-able down the road. The difference in cost might not be all that bad especially if you can find a complete donor boat.

                    The Bravo and Alpha GEN-II and others have the same transom stud pattern (and same number of studs)

                    The drilling template shown below is Mercury Marine 91- 43693A2

                    According to MercStuff, It will fit 1976 to Date Pre-Alpha, Alpha One, Generation II and Bravo drive units.




                    I seem to remember the Mercruiser Bravo transom having the 2 additional studs at the top so if you go to an Alpha Gen-II or Bravo, you'll be drilling 2 additional holes. (Don't know if earlier Alphas have those two additional studs, but the bolt patterns are identical)

                    I didn't have the above drilling template but got close enough only having to drill 2 holes. That template is pretty pricey. ($400-500) but you might be able to find one used and I would expect it'd re-sell close to whatever you pay for it.


                    Even if you stick to the Cobra transom and SEI adapter/drive, you'll be happy with the performance!


                    Take pictures!!

                    We love pictures!


                    1987 FourWinns 211 Liberator, Originally an OMC 460 King Cobra.
                    Re-powered in 2006 with a 1997 Mercruiser 7.4L Bravo III

                    Comment

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