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406ci yamaha stern drive gear murder??

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  • 406ci yamaha stern drive gear murder??

    hey guys,

    deffinately wanted to gather up all the lose change floating around out there.
    maybe find someone who already has this t shirt.

    my buddy and i have been working the past year or so on a project, which consists of a 1994 monterey 19scr (open bow skiboat) with the yamaha (gm 4.3, and yamaha sterndrive) we bought the boat for a 1000bucks mint condition, and trailer, other than the fact that we knew it either had a cracked head or block. we were fully prepared for the road ahead.....
    the boat is in really condition, the guy we purchased it from went through a divorce and neglected winterization, so we swooped in and now have a boat that will potentially be a lot of fun here soon.(ended up being a cracked block) We decided to go with a 406 small block to replace the original 4.3. yes a late 70's model powerhouse with the double hump heads. has a mild cam, holley 650, and some decent internals, came out of my buddys c-10 who ran into some legal issues and needed cash, so another 1000bucks later, its mine, bought some univeral 350 exhaust manifolds, used the the existing cooling hoses , parts ...etc to convert it, right now its a well known GM performance specialist shop in raleigh getting dialed in, i needed it done right the first time, haha. anywhoo...........my question is, with this yamaha stern drive being for the 4.3, will this gear ratio in my sterndrive cause problems, does the 350 monterey boats of similar year have different ratios? i have looked around on the internet(briefly) for this information, and havent called around either. i was wondering if anyone knew off the top of their head what i was working with, and what route i could take if i needed to beef it up to handle the new power. i have not yet had it in the water, and i wont know if there is even a problem until then. i m just doing my homework, thanks for any help.

    ben



    ...if it floats, flys, your just better off renting it
    Last edited by Don S; August 30th, 2009, 07:53 AM. Reason: Cleaned up signature line

  • #2
    Re: 406ci yamaha stern drive gear murder??

    You would need a completely different gear ratio for a V8, especially with a built up V8, or you would be wasting all you were trying to gain.
    Another problem you have is finding somewhere to find Yamah parts and service to change the gears.
    There is VERY VERY few who can do this. Yamaha sterndrives were only in the US of a very few years back in the early 90's.
    Might want to contact Capt Ken for Yamaha help.
    Don S.


    Please, no PM's (Private Messages) regarding boat/engine problems.
    That is what the forums are for.
    Only forum/moderator issues will be answered in PM's.

    Comment


    • #3
      Re: 406ci yamaha stern drive gear murder??

      thanks for the prompt response

      the other manufacturers of sterndrive units, is there any possible swap?my friend actually has a 94 monterey 350, his unit is yamaha aswell, could that be a route? or once you have a yamaha, your doomed from the start?

      and the current gear ratio, are we talking high rpm rev limiter busting 30mph cruises, shooting a rooster tail(which wouldnt be so bad haha) and will the torque this ol girl is going to spin off rip these gears ?

      Comment


      • #4
        Re: 406ci yamaha stern drive gear murder??

        I have no idea about Yamaha outdrives, your best bet would be to find a doner boat with a Mercruiser or Volvo engine and outdrive setup (with the proper gear ratio) and swap everything over.

        The problem with not changing gear ratios, is this. The props are designed to need a roughly 17 to 21 pitch prop for best running both getting on plane and top speed. When you go to a lot steeper prop to keep your WOT rpms in the correct range so you don't overload or over rev your engine, You may get top speed, but poor performaned when starting out. Slow to get on plane, low power, etc.
        As far as props go, who knows if anyone even makes a Yamaha prop with enough pitch to even pull it off. Of course the gears are also ligher made for the V6 ratios as well.
        Don S.


        Please, no PM's (Private Messages) regarding boat/engine problems.
        That is what the forums are for.
        Only forum/moderator issues will be answered in PM's.

        Comment


        • #5
          Re: 406ci yamaha stern drive gear murder??

          The (good natured) smart alec in me want's to ask why you didn't put a studabaker engine in it, but I'll spare you the peanut gallery comments...

          I was really comfortable "overpowering" a merc alpha one drive because they're very, very common, parts are easily available, lots of techs and info how to work on them, back some years ago they were used on a lot of fast boats and people are still around that know how to set them up, and finally because there are a lot of great props new ones and used ones floating around for all sorts of pitch ranges. I have very good stainless props ranging from 19" through 29" that will fit on a merc alpha or bravo drive. Plus you can buy a new / rproduction unit for $1200 - $1300 which is cheap when you start dealing with drive swaps. had that not been the case or had I been doing it with anything but a light boat, I would have gone with a merc bravo set-up.

          if you do want to change to a different drive, it would think that's the most logical direction to look. not going to be cheap because you'll need everything. and i don't know about the transom, etc... but will hold up well for what you're doing, lots of parts and technicians available, aftermarket replacement available, tons of props everywhere from something like 15" through 32" easily available at "reasonable" (less than custom shop) prices, etc... Good luck with it! will be interesting to read which way you go and how it works out.
          Just another moron with a computer and too much time on his hands...

          typical rainy afternoon on the river... http://www.youtube.com/watch?v=8Izi3v75jTs

          more recent, amateur camera operator for sure!... http://www.youtube.com/watch?v=EHoXsQc6644

          Comment


          • #6
            Re: 406ci yamaha stern drive gear murder??

            i dont even know what is in a studibaker to be quiet honest with you.

            i just know that everything for hte most part has bolted right up, and has been cheaper, to an extent* than buying a reman'd 4.3. we plan on putting a wakeboard tower and needed some down low power and on top of that i really wanted to hurt some feelings out there , 4k$ boat with 350hp-400hp motor that'll easily get some attention. id love to give a baja , or even a new mastercraft or malibu a run for their money. i just dont know how much running or for how long a run that'll be for with this outdrive situation. i like to have toys that aren't generic. theres a lot of guys out there with exactly that, and i want to pull up to the dock with the motor count'em off so to speak in basicall a stock looking ski boat, then be able to shoot across the lake raising all sorts of hell. but i dont know if i can have my cake and eat it too. i imagine this outdrive will last the rest of this season, then this winter look into gettin a new entire unit back there to handle this. but again, i havent even taken it out, so right now wishful thinking

            Comment


            • #7
              Re: 406ci yamaha stern drive gear murder??

              Studebaker was just a car that was made a good while ago and is hard to find anything for... probably not a good anology.

              400 should be a great engine for pulling boarders, etc...

              is the prop shaft configuration compatible with any other brand / application props? that will have a lot to do if you can find props for it... and do you know what the gear ratio is?

              Am I correct that yamaha made two sterndrives configurations: one for v-6 and down and another for v8?

              either way, maybe we'll see you on Jordan or falls one of these weekends...
              Just another moron with a computer and too much time on his hands...

              typical rainy afternoon on the river... http://www.youtube.com/watch?v=8Izi3v75jTs

              more recent, amateur camera operator for sure!... http://www.youtube.com/watch?v=EHoXsQc6644

              Comment


              • #8
                Re: 406ci yamaha stern drive gear murder??

                I broke a couple alphas with my 406 and I just fish. Had to swap to a bravo.

                The Yamaha was copied from the Volvo so I suspect it would have heavier gears than the alpha but there is a potential gear ratio problem. That's also the reason Yamaha can't sell their drive in the US anymore. Copyright/patent infrigement.

                Capt Ken is only one I know of who has Yamaha parts available...as Don said.
                Charlie

                Comment


                • #9
                  Re: 406ci yamaha stern drive gear murder??

                  We decided to go with a 406 small block to replace the original 4.3. yes a late 70's model powerhouse with the double hump heads. has a mild cam, holley 650, and some decent internals,
                  Howdy,


                  So I guess the 406 had the correct flywheel, and bell-housing bolt pattern to match the 4.3? Very lucky.......The coupler bolted to the flywheel too? even more lucky!

                  Then you were able to find marine, cast, jacketed manifolds (isn't the 406 similar to a 350?) that will bolt to the heads and match up to the Yamaha Y-pipe? or did you just run them "thru-hull"? also pretty lucky....

                  (I did a little self-informing and it appears that the 406 is a "small-block" chev engine that will go where any 283/327/350 etc engine will go........COOL)


                  What you have will probably work. Your drive is probably a rather "high" ratio for that engine I suppose. Unless you can read it on the drive or get it from the model/serial number, you can simply turn the input shaft on the drive 20 turns or so and have someone count the output (prop) turns to calculate the ratio.


                  Most all (stock) marine engines don't turn anymore than about 5100 max. ....Some are less (my 454 has a recommended WOT of 4400-4600 RPM, rev limited at 4700)

                  So all the (2! ) drive manufacturers design the drives and props with this in mind. The engine manufacturers "cam" the engines to make best HP/torque below 5000 RPM generally.

                  The racing people, do something else....(Of course!)



                  The correct ratio for a SBC is around 1.5-1.7:1 in round numbers....That drive if it's correct for a 4.3L engine might be around 2.0:1

                  That might require you to put a rather "tall" prop on it which will put it out of the efficient range of prop pitch as Don indicated.....

                  I'm not saying it won't work, It just might not be very efficient. You might get good top speed but might cavitate all over the place during a WOT holeshot. (you might also break the drive or spin the coupler too!....and this on a drive that has maybe 1 or 2 US sources for parts)


                  Having said all that, TAKE PICTURES! post them on Photobucket so we can all see!

                  Sounds like it's going to be a pretty neat project!


                  If it were me and I just HAD to use that built up 406 (and it does sound like a cool engine) I would find a Bravo drive and gimbal and sell all that Yamahama stuff on ebay.


                  Good luck..... (PICS PICS PICS!!)


                  Rick

                  Comment


                  • #10
                    Re: 406ci yamaha stern drive gear murder??

                    yea im hoping to make a couple test runs this week out at falls, i like the 24 hr boat ramp its easy access, and on top of that theres usually a lot of folks out there to help tow someone in! i live in garner so its not to bad a hike, hopefully ill find out all i need to know possibly by thursday, and then if all goes well jordan lake for the weekend......the funny thing is memorial day was our first goal to get it on the water, then the 4th, now labor day, who knows haha!

                    i really appreciate everyones input btw. i was unaware that yamaha isnt allowed to sell b/c of copyright laws, and as far as prop goes......yea its gonna be a little tricky, im just going to make a couple runs keep my eyes and ears open see what shes telling me, i would like to think i could hear some serious whining, or other problematic noises coming from the outdrive etc...does anyone know a good website for ss props? ive seen a few out there, j/w if yall had a really good site that was really good.

                    as soon as i get the boat back which should be tomorrow its looking like now, ill let yall know about pic posts,over at mayhem motorsports they have it really cleaned up and everything is looking good,the guys had some problems with my old altenator, it was being difficult and they were suggesting a one wire altenator, we used my existing wiring harness, i dont know why there is trouble, but anyways.

                    one of my friends was telling me earlier (pre 406 install) that sbc should bolt right up, and it did, the flywheel , we had to do some hw, but my roomate manages a precision tune, had one of his mechanics peek at the situation(real old school dude) and after that just a phone call away to advance auto and it came from an older year model vehicle, i swear she was heavy, wanted an aluminum flywheel, but money talks! the exhaust manifolds came from a place of ebay, and the store is actually on the outer banks here in NC, they were a universal fit 350 exhaust manifold, complete with risers and hardware. we had to paint them with the high temp paint, they bolted right up, and we have some exhaust elbows that the guys at the motorshop used , same material that is designed for turbo's ( thats what they specialize in) so its a perfect fit to the Y pipe
                    we had to custom make some brackets for the altenator, power steer and raw water pump, i actually had to search online for 2hours for that raw water pump rebuild kit, and it actually came lewis marine right here in NC aswell, there is a bench seat we had re upsholstered and it sits in front of hte motor, we may have to adjust where it exactly sits , the 400block is obviously longer, only thing there is a deck lid that rests on top of the bench seat and is bolted to a hinge at the rear of the boat and has hydraulic arms that raise and lower . so im going to have to tweak that a hair, there was a bunch of nights where we just wish we went with the 4.3, but if you follow what everyone else is doing you'll never get first place

                    thanks for all the help

                    Comment


                    • #11
                      Re: 406ci yamaha stern drive gear murder??

                      .....well, after i had iboats resend my password and login info. Here I am. Been almost a year..haha, anyone guess why?.....time , money, headache......

                      Good news*

                      The Dirty Girl is sporting a new floor, new carpet, reconstructed, and re-vinyled bench seat, and deck lid.......and a fully functioning 406sbc! The performance shop here in Raleigh ( mainly specializes in GM performance) finally got their act together, and we are dialed in. Went through two carbs, now sporting an edelbrock, two fuel pumps, now sporting a Holley, which according to the guys a Mayhem, will support anything. So now we just hook it up, dump it at Sherron Harris Lake, help the girls on the boat, and haul *** to our cove(s). Now its time for a new prop, duh, thru hull exhaust, window tint, audio, and a monster wakeboard tower. The summer is looking rather promising at this point.

                      considering a ss prop by solas. either possibly a 4 blade 25-27 pitch
                      any suggestions?
                      shes makin good power mid 3-4500 , and of course she'll scream at 5500, but we dont hold it there for long. I'll be purchasing one soon. need my top end!

                      Comment


                      • #12
                        Re: 406ci yamaha stern drive gear murder??

                        Hey!



                        I think you promised pictures!!!!


                        What sort of performance are you getting?

                        Comment


                        • #13
                          Re: 406ci yamaha stern drive gear murder??

                          Pictures are around the corner, I have some restoration, old motor removal, new motor....etc pics I need to round up. Plus, I need some new ones, only after this Dirty Girl gets a bath.

                          Performance wise, I'd say (based on jet ski who thought they were going to dust us) shes running strong, and I am thoroughly impressed with how everything has finally come together. Considering our budget, and all the custom modifications, and severe headaches we have dealt with , I am happy. Best guess our top speed is around 45, our speedo is broken, taking handheld GPS out next time. Shift cables need replacing, 16yrs old is a good indicator why, and the fact that she has a hard time finding neutral. Drives like shes on rails, and could pull the devil outta hell. New prop, cables, and thru hull exhaust, and we'll have the cheapest, fastest, loudest boat on the lake......and the hottest ladies, but I can take my john boat out for that one *

                          Comment


                          • #14
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                            Re: 406ci yamaha stern drive gear murder??

                            Hmm,


                            With a 19' boat and a somewhat tricked (big) SBC, it should go pretty quick with the right prop on it. I would say easily 60 mph on smooth water.....(be careful!!)


                            You can do some ball-park figgerin with a prop-slip calculator.

                            However, you MUST know the drive ratio, RPM and speed accurately to get meaningful numbers. RPM means you need a known tach (a lot of them are way off at the upper end) GPS is great for speed. Do you know your drive ratio?


                            http://www.go-fast.com/Prop_Slip_Calculator.htm


                            I love it when a (neat) plan comes together!

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