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Yamaha 4.3L Exhaust Manifolds

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  • Yamaha 4.3L Exhaust Manifolds

    Good morning,

    I am just in the stages of replacing the 4.3L GM in a 93 Rinker I purchased. It has a Yamaha sterndrive setup which, until recently, I was unfamiliar. I now realize that parts are not easy to locate. I have a cracked exhaust manifold. Does anyone know where I can come up with an exhaust manifold for a Yamaha 4.3L set up or is there a reliable way to repair?

    Thanks in advance.

  • #2
    Ayuh,.... Welcome Aboard,.... I believe yer only option is to adapt a set of Merc manifolds,....


    • #3
      Thank you. Lots of good information here. Adapting over is what I was starting to think. I can't seem to find anything anywhere. I am planning to call Capt Ken tomorrow. Are there any Merc adapter kits you would recommend?


      • #4
        Ayuh,.... I doubt there's any "Kit",....

        The motor side will be the same,....
        You'll need to figure out which risers ya need to mate up to the Yamaha y-pipe though,....
        Diameters, angles, 'n lengths are the variables,....


        • #5
          There is no kit. You pretty much buy the merc manifolds and risers and gasjets and modify your y pipe as needed
          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 - http://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"

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          • #6
            Got it. Thanks. I guess I will start getting measurements around.


            • #7
              I've done the swap for the 5.0/5.7 and 77searay197 has done a 4.3. I even did a Youtube video to show the setup. You have to reuse your risers. I posted a write up on the things used with some part numbers for the 5.0/5.7.


              • #8
                Hope this helps...



                • #9
                  Thank you Antax!


                  • #10
                    Hi Trent
                    I am in the same predicament as you. What did you end up doing?


                    • #11


                      • #12
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                        Interesting, it appears that Yamaha wanted to have a 'warm manifold' system like Merc did on some of their models, the idea being that keeping the manifolds as warm as the block would evaporate any condensation in the exhaust and reduce the chance of water being sucked back in the exhaust at low speeds where the engine is running cool. Not sure if this would work but you may have been able to use Volvo manifolds with a Volvo thermostat housing which would have been simpler as far as the plumbing goes, not sure if they would mate up to the Yamaha Y pipe. VPs system is a cold manifold system though where the manifolds are usually cooler than the block by a considerable extent.
                        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"