1991 cone clutch king cobra transom hole

Fourwinns235

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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?
 

Lou C

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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).
 

HT32BSX115

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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
 

aimlow

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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.
 

Lou C

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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.
 

HT32BSX115

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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.
 

Fourwinns235

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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.
 

Lou C

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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.
 

Fourwinns235

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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.
 

HT32BSX115

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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, [FONT=Verdana, Arial, Helvetica]It will fit 1976 to Date Pre-Alpha, Alpha One, Generation II and Bravo drive units.[/FONT]

transomfixture3.jpg
wAAACH5BAEKAAAALAAAAAABAAEAAAICRAEAOw==



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!
 

Fourwinns235

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I just purchased a 1995 omc cobra with a 5.0 efi and the joint venture omc outdrive that has the same horsepower at the prop of my cone clutch king. Did some research on parts found the only part that is hard to come by is the ecm. Me having a creative mind found a way to clone the ecm from a mustang. By copying the fuel tune from the original omc to a programmable chip of the mustang. That being out of the way and no worries there I am going to transfer all of the Ford and Volvo stuff in place of the Chevy king cobra. The only transom work that needs done is to fill the top 2 holes. Everything else is bolt on. I may need to get a couple of cables. I think the fuel injection will be way cool. If anyone knows anyone that needs a functioning king cobra cone outdrive or transom mount I will soon have it for sale. Plus if anyone needs an ecm for 5.0 I can make one for them.
 

Lou C

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That's very interesting, what will you have to do to make the Mustang ECM work? Would love to see pix as you go along...
 

HT32BSX115

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Me having a creative mind found a way to clone the ecm from a mustang. By copying the fuel tune from the original omc to a programmable chip of the mustang.
Evidently, the Ford ECM uses a fairly standard EEPROM? There's probably several EEPROM programmers out there in radio land and the marine "code" wouldn't likely be all that complicated.

You won't have to worry about finding a replacement ECM now. You'll just have to worry about some of the hard parts in the drive that are no longer available.

I think there's even raw water pump impellers available now too! (they weren't for a while and got very expensive)

Just be glad you don't have a 460!!
 

Lou C

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If its the joint venture drive with the engine mounted impeller, the parts should be the same as for a '95 Volvo SX with the same engine....
 

HT32BSX115

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I just purchased a 1995 omc cobra with a 5.0 efi and the joint venture omc outdrive that has the same horsepower at the prop of my cone clutch king. Did some research on parts found the only part that is hard to come by is the ecm. Me having a creative mind found a way to clone the ecm from a mustang.

Using that drive will solve your (drive) hard parts "problem" other than the FOMOCO specific irritants like manifolds etc....They're no problem finding but can be a little more expensive since they make FAR more GM engine parts than for Fords.

You also might be able to install a 5.8L engine which would give you at least similar performance to the GM 5.7. That should be all that hard to get the EFI set up correctly too.

A 5.0 L engine(EFI or carb) in a boat your size is not going to be any power house. Since you're switching to an SX transom and gimbal, you're also able to install a Volvo DUO-Prop drive. That with a tuned up 5.0L might be an OK performer.

My 21ft Four Winns 211 Liberator was a real dog outta the hole before with the OMC 460 340hp(crankshaft) single prop drive. Skiers hated it because they got dragged through the water for a while before getting up on a plane.

With the dual-contra-rotating prop Bravo III with similar hp (GM 454, 330crankshaft HP) the difference was nothing short of incredible. Top speed was a little lower though because of the built-in RPM limit.

Good luck on the project!
 

Lou C

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Ya got me thinking Rick...if I ever have to replace my Cobra....to convert it to an SX....DP....might really wake up this sleepy old FW.....
Meanwhile the 30 year old Cobra drive...works as new....the major parts issue for me with the OMC was the one piece exhaust, easily fixed with the upgrade to the later OMC/Volvo 2 piece exhaust....it all bolted up and fits like factory, just using the expensive V/P 90* aluminum exhaust pipes and hoses....but for replacements (needed here in the salt pond every 5-7 years)...I can use the less expensive but good as factory Barr exhaust parts....

I also still have the Quadrajet...which I rebuilt myself and works fine...but bought the parts for the later Holley models, if the Q Jet gets corroded to the point where I can't rebuild it, I have the Holley 4160 used on these engines, the adapter, fuel line etc.
 

HT32BSX115

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Ya got me thinking Rick...if I ever have to replace my Cobra....to convert it to an SX....DP....might really wake up this sleepy old FW.....
Lou,

I have noticed that Merc does use the Bravo III from the 4.3L engine and up and I must presume that VP does as well. I am still shocked at the difference in over all performance with essentially the "same" crankshaft HP.

I remember when my Brother bought this boat new. He actually drove a 454/Alpha powered 211 and because the 460 had slightly higher HP (340 vs 330 :facepalm: :rolleyes: ) He got the OMC!

Of course, in 1987, no one would have even DREAMED OMC would "disappear"!!

At first, he thought there was something wrong with the engine because it was so "slow" getting up on a plane. My Dad could actually beat him out of the hole, and up to about 35mph with the 66 150hp Mercruiser MarkTwain 18ft (that I eventually ended up with in the late 90's, sold in 2006 after I had the Four Winns for a year or so..)

In the late 90's, After an insurance covered block-freeze event, My Brother took the money and had the 460 rebuilt by some "460-guy" in Redding, Ca that supposedly tricked it out a bit to make the boat run better (outta the hole) It didn't.

And he tried everything incl adding Bennett Tabs, every king of TRIM position, etc but short of building up a "FULL-Race" 460 which he could've done but never wanted to spend that kind of money on.

Once on a plane, it ran fine and was pretty fast. It just took a while to get there. WOT RPM/Speed were just about right.......it was just a little slow out of the hole (since new)

After I put the 454/Bravo III in it, my brother was visiting that Summer and once he drove it, he wanted to buy it back from me! He couldn't believe it!

I think putting a DP on yours would make a huge difference even staying with the same engine, Although, a 20ft boat with an SBC _ DPS drive would REALLY perform good for many years to come.

The thing I like about my Four Winns 211 (1987) is the license tags are only about $25 per year. and the insurance is pretty cheap too!

For something I only use once or twice a year during Summer, it makes it pretty cheep to keep! :thumb:
 

Lou C

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I'm going back and forth with that idea (eventual re-power and Volvo DP SX drive) since I did a top end overhaul in '17. Not sure how long that's going to last but so far so good. Here in the salt pond, used boats are a crap shoot if they are any older than 5-7 years old, even outboards sometimes. My idea of the re-power is attractive to me because I can do a lot of it myself, more learning process, but the issue is that the value of the boat (insured for $10500 agreed value policy) is not all that great so a big investment gets kind of risky. Then there's the maintenance in salt water (moored) which is getting old as I get older, lol. So my other idea is to spend a lot more money and get a new outboard powered boat. I found a 2 year old Key West DC 20' that has about 75 hrs on it (Yamaha 150 4 stroke OB), still under warrantee. About 32K or so. That would solve a lot of the aggravation of boating here for me. Don't want to let the old boat go just yet but I just want something I can depend on, to take a ride across LI Sound to Conn on a nice day (only about 9 miles across LI Sound). I like the idea of the Evinrude 10 year warrantee but Yamaha and Mercury are pretty dominant here....Also don't want to give up the simple GM marine cast iron engine since I can start new with a long block V6 for about 3,000 and add closed cooling. But time is the most limited resource and old boats take time...
 

HT32BSX115

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I'm going back and forth with that idea (eventual re-power and Volvo DP SX drive) since I did a top end overhaul in '17.

Yeah. A 5.7L VP/DPS would run pretty nice in that boat. You could also install closed cooling and dry-joint type manifolds/risers (if VP has those) and you'd never have to worry about salt water or winterization again!
 

Scott Danforth

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volvo DP's behind the 4.3 are 2.15:1 ratio, behind the SBC's are 1.95:1 ratio and behind the BBC's are 1.78:1 ratio.

once you go with a duo-prop drive, you will never go back.

they even have duo-prop surface drives now.
 
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