OMC-King Cobra-- 496 XR or Bravo Conversion

[THEDONZ33]

I would like to know what the issues I face for a
351 OMC King Cobra to a Merc 496 with either an XR or Bravo Drive.
Will there Be major issues with;
1. Motor mounts
2. Drive mounts
3. Drive Bolt and cut out patterns
4. X Demension

Any advice, reccomendations or experiences would be extrememly helpfull in planning for the repower

[gcarter]

Is it a hump back King Cobra? If so, and it's in good condition, many here would tell you to keep the drive and look for an OMC flywheel cover for a BBC, they are around.

[mrfixxall]

I would like to know what the issues I face for a
351 OMC King Cobra to a Merc 496 with either an XR or Bravo Drive.
Will there Be major issues with;
1. Motor mounts
2. Drive mounts
3. Drive Bolt and cut out patterns
4. X Demension

Any advice, reccomendations or experiences would be extrememly helpfull in planning for the repower

the only problen i would see rite now is coming up with the 50 grand for the conversion..

What george said! keep the drives and find the engine pkg's

[THEDONZ33]

Is it a hump back King Cobra? If so, and it's in good condition, many here would tell you to keep the drive and look for an OMC flywheel cover for a BBC, they are around.

Whats the difference between a standard and a humpback King Cobra? Any one have pictures for comparison ?

[gcarter]

The humpback has the pump in the top of the drive and has a peculiar hump on top of the upper gear case, also it has very strong internals.
The other has a flat top upper gear case.
Sorry, don't have pictures.....

[mrfixxall]

if you have a 1990 or 1992 or newer then you would have the hump back kc drive,sorry i forgot the year,but if its 89 or older then you have the standard king cobra which is still a strong drive..

post a pic of what you have or google omc king cobra and you can see the two..

[THEDONZ33]

pretty sure its a humpback
1993 and If i can figure out to up load pictures I would attach one. (When i try to click the insert image icon all i get is a bell ring)

[mrfixxall]

pretty sure its a humpback
1993 and If i can figure out to up load pictures I would attach one. (When i try to click the insert image icon all i get is a bell ring)


send them to me! mrfixxall@sbcglobal.net ill post them..

or better yet bring it to my shop in glen ellyn and we will have them out in no time:)

[Walt. H.]

Your 93' hump back K.Cobra with cone clutches will look like this.

[MOP]

The King's have a belt driven sea water pump, the standard haas the pump in the drive. The hump on the King's was so it could handle high torque applications when run in reverse rotation, the massive cap eliminated the possibility of driving the vertical shaft up through the top of the drive. The drive is over engineered, very strong and also more hydrodynamic. Withe exact same power it is faster through the water. It is quite a bit stronger then the Bravo maybe even stronger then the XR. We have yet to see any member blow one, cannot say that about black on back!

[RedDog]

RickR chipped a tooth in his by hitting a stump or log before I bought it from him. Seems I remember they are rated to 650HP?

[Barry Eller]

The King's have a belt driven sea water pump, the standard haas the pump in the drive. The hump on the King's was so it could handle high torque applications when run in reverse rotation, the massive cap eliminated the possibility of driving the vertical shaft up through the top of the drive. The drive is over engineered, very strong and also more hydrodynamic. Withe exact same power it is faster through the water. It is quite a bit stronger then the Bravo maybe even stronger then the XR. We have yet to see any member blow one, cannot say that about black on back!
Phil, my King never had a belt driven sea water pump. I do have the Humpback, cone clutch type. It is a 1993, originally mated to the OMC 454HO King Cobra. I still use the drive water pump. The only thing about the drive pump is the plastic housing, I have to keep the engine rpms low when running on the hose to keep the impeller from melting the housing. You cannot get enough water flow from a hose. I do use the muffs that flow water from both sides.

[mrfixxall]

Somthing to think about..

http://stlouis.craigslist.org/pts/1609506239.html

[Barry Eller]

Somthing to think about..

http://stlouis.craigslist.org/pts/1609506239.html


That IS a photo of a GEN VI BBC. I don't think OMC was in the stern drive business in the years stated though. With them having a core charge, I'm thinking rebuilds.

[Walt. H.]

The King's have a belt driven sea water pump, the standard haas the pump in the drive. The hump on the King's was so it could handle high torque applications when run in reverse rotation, the massive cap eliminated the possibility of driving the vertical shaft up through the top of the drive. The drive is over engineered, very strong and also more hydrodynamic. Withe exact same power it is faster through the water. It is quite a bit stronger then the Bravo maybe even stronger then the XR. We have yet to see any member blow one, cannot say that about black on back!
No engine mounted sea pump Phil, just the easy to service "like a distributor cap" shown disassembled pictured below.

[THEDONZ33]

This has become a very interesting thread, I had no idea this type of information would pop up regarding this topic.
I hope what my concerns here, in the original question will be served very well by how this thread is developing, so that others will find this information as valuable as I am.
I am in the process of buying a 1993 Classic 18 with a 350 OMC Mated to a humpback King Cobra Drive.
My concerns are that since I AM a Mercruiser and Guy, and that I would like get away from a carburated motor (and Repower) to an EFI 496HO (425 HP) Mercury Power plant. I am wondering what speed, performance and reliability advantages I can expect from this conversion IF any.
Is there an OMC EFI equivalent to the MERC 496HO- 425 HP? and What Drive would Be a reliable mate to satisfy my objectives ?
I would also like to convert to through transome exhaust with a silent choice opotion and external steering, and upgrade the bennet tabs to Kiekhaefer's
(I know thats probably overkill)

Advice, Opinoins, Suggestions, and any comments Are all very welcome !!

[gcarter]

Dr Dan, a member here has an early '90's 22C w/a 500 (I think) and a KC. It is one of the fastest 22s around. It would be faster but it's somewhat difficult to mount external hydraulic steering on this package. Last I heard, he was piecing together a steering system and it will be faster yet.
The difference between his boat and others here is the KC drive. It's simply a faster drive.
Funny how sudh little things can make so much difference.

[mrfixxall]

This has become a very interesting thread, I had no idea this type of information would pop up regarding this topic.
I hope what my concerns here, in the original question will be served very well by how this thread is developing, so that others will find this information as valuable as I am.
I am in the process of buying a 1993 Classic 18 with a 350 OMC Mated to a humpback King Cobra Drive.
My concerns are that since I AM a Mercruiser and Guy, and that I would like get away from a carburated motor (and Repower) to an EFI 496HO (425 HP) Mercury Power plant. I am wondering what speed, performance and reliability advantages I can expect from this conversion IF any.
Is there an OMC EFI equivalent to the MERC 496HO- 425 HP? and What Drive would Be a reliable mate to satisfy my objectives ?
I would also like to convert to through transome exhaust with a silent choice opotion and external steering, and upgrade the bennet tabs to Kiekhaefer's
(I know thats probably overkill)

Advice, Opinoins, Suggestions, and any comments Are all very welcome !!

That motor combo in a 18 will be to heavy for the boat and the performance won't be what you would expect..that boat with its set up should do 63-65 mph,with a bigblock in it the boat handle as good as if it were a small block..i would look into a 383 pkg with a bravo drive then add a -2 shorty and that boat should do 75+ all day long,even better get ahold of a blackhawk drive and you will see 80+ :)


ok first post i say 351 assuming its a ford motor,now i see you posted a 350 which is a chevy motor? which pkg is it? :)
And i saw a z33 cross bow and assumed you were upgrading the engines in their..

[THEDONZ33]

Like every body else and thier Brothers I dont mind a worked Motor, I just dont want to be working on the motor constantly, I would gladly trade off a few MPH for reliability......
but only a few :shades:
I would be very satisfied breaking 80

[THEDONZ33]

I got rid of the 1990 Crossbow (with Merc 454 Gen IV 365 hp blocks) last year...
Now I am replacing it with the little sister 1993 Classic 18 and she has the Ford 351 and King Cobra humpback
So I am starting some research for the 18 Classic which should be im my drivway by the time the ice is gone. I plan to run the 18 as is this season then start the upgrades one at a time each off season

[mrfixxall]

Like every body else and thier Brothers I dont mind a worked Motor, I just dont want to be working on the motor constantly, I would gladly trade off a few MPH for reliability......
but only a few :shades:
I would be very satisfied breaking 80

theirs a guy on here? i think but he has a bone stock 300 hp efi 18c with a blackhawk and he is brakeing 80 mph..

so with one of thease badboys you should see more :)


http://www.marinepowerservice.com/BoatingStore/browse_detail3.cfm/productID/38838.cfm

P.s.

If you see a white yellow and purple donzi x18 that reads SAY BYE BYE on the back on the chain this year stay away from him,he is nuts!!

[THEDONZ33]

What about the motor mounts, Are thier huge issues, or is it an easy conversion from OMC to Merc ?

[mrfixxall]

What about the motor mounts, Are thier huge issues, or is it an easy conversion from OMC to Merc ?


that depend on which motor mounts are in the boat,they may be stringer mount that through bolts through the stringer or it could have a aluminum angle that's though bolted through the stringer that the motor mount i bolted to..its not that hard to convert it but either way its a piece of cake to do..now if you do decide to go to a BB then your stringers may not be wide enough or strong enough to support the weight so you may have to do some glass work their to support it..

[THEDONZ33]

I need to look into it much more but I like that 383 stroker Scorpion option so far.... Like I said doing early research so I know how big of a crow bar I need for my wallet next off season

[mrfixxall]

I need to look into it much more but I like that 383 stroker Scorpion option so far.... Like I said doing early research so I know how big of a crow bar I need for my wallet next off season


BTW if you decide to add silent choice i would wait until you decide what engine combo you are going with,so your not paying the xtra cash to plug holes and re cutting the transom for the correct tip height or width..

I like EMI http://eddiemarine.com/store/cart.php?m=product_list&c=300
Silent select,they have a linear actuator which you can adjust the tone going out the back of the boat,their adjustable form 0-100% open..not like the others either on or off..

[CaribouLou]

Any word on this? I just rebuilt my cone clutch King Cobra, and its finally acting the way it should.....

[deanco]

Why not just trick out the 351? If its the 5.8L EFI, its EZ to take out, EZ to get rebuilt, no conversion necessary, and best part - its a Ford and EZ to fix (too bad they do break). The OMC Cobra drive will handle the extra boost (do you have through-hull pipes or silent drive?) You can pony that baby up to 400 HP no problem - whattay want? with 400 ponies you should do 90, no sweat (I have 300 in mine and do 70). make sure you have good extra trim tabs, just in case (the OMC Cobra tab is the best). Good luck.

[The Hedgehog]

I saw Dr Dan's steering cap. It was a nice piece. I don't think he pulled the trigger on it. My guess is that you can find another.

[CaribouLou]

I'm going to need external steering come this winter....And I'll be testing how strong the cone clutch King Cobra really is....

[Dr. Dan]

I saw Dr Dan's steering cap. It was a nice piece. I don't think he pulled the trigger on it. My guess is that you can find another.

I have a Steering Bracket for the King Cobra, it is a Marine Machine peice, it is very expensive, I will still need to connect it all to whatever Steering System I will be using, so collectively its gonna be a little over $4K easy by the time its done.

As for the King Cobra, I have an HP500EFI connected to the King Cobra, Rear Motor mounts for the original 454 were the same and are still in use, sort of...the boat is down since its Roller Bearing exploded and took out the Cam Shaft, Timing Chain and related running gear. I am real close to resurecting the Donzi, Karma has extended some of the build time. But it is on the horizon.

The King Cobra Drive has had a new shift cable installed and one Cone Clutch installed. Otherwise the Drive has been bullet proof. The 22 Classic was a turn key 80 mph boat for 5 years. I run 25 and 26 TXP Turbo Props with flo torque hubs.

I have a newer boat with an XR also and I am pretty sure the King Cobra is rated heavier duty than the XR. I buy my replacement parts at Fast Eddies Discount Parts 800-531-4486. www.fasteddiesdiscountparts.com I speak with a Brad, they are in the Carolinas...very nice folks.

Any direct questions feel free to shoot me an email @ drdan93@comcast.net I am not on here much anymore.

Good Luck

Danny

[CaribouLou]

Email sent Danny