OMC "daddy" King Cobra - new owner, things to check?

I just picked up an old 1990 Donzi Black Widow with the cone clutch style late model king cobra. The boat has been restored, but the engine doesn't run (pretty sure it's something simple like a valve / pushrods.. Said it ran but made no power and rear cyl had no compression) but at the price I got the thing for, I'm not worried about it.

When I do get the engine rebuilt, what items should I check or replace when I get ready to put her in the water for the first time? How can I check the alignment of everything? The boat is 24' with a 454 and it has a 3 blade 19" viper ss prop on it now, which would seem a little small? Previous owner said it ran in the low-mid 70s (no its not a regular 454 lol). I'd rather prop it for top end and cruising over hole shot.

The boat was converted to thru-hull water pickup direct to engine water pump. I don't know much about this other than that some others complained of water flow problems with the king cobra also? Is this good or bad, and what will this change when I service stuff.

I'm most concerned about anything rubber.. Seals etc.. And the overall alignment of the drive. Should I take anything apart to check it? New fluids?

Also how can I check the shift adjustment on this guy?

I've got a manual coming in the mail but I'm curious if anyone has first hand experience.

Re: OMC "daddy" King Cobra - new owner, things to check?

Congragulations on your purchase. These drives are dependable, however parts are imposible to find. Make sure to check your gimball bearing often, couplers and bell housings are nearly impossible to find. I recomend reading up on the manual and replacing the lower shift cable when they become too dificult to adjust. As for the engine, good thing it is a 454 and not a 460 (more impossible to find parts). engine parts are available for 454 from a aftermarket or gm source. As for the drive, a pressure test should indicate any leaks. have fun and be patient. These are good machines, however they recieved a bad rap from mechanics who were not trained specificly to work on them.

Re: OMC "daddy" King Cobra - new owner, things to check?

kmarine said:

Congragulations on your purchase. These drives are dependable, however parts are imposible to find. Make sure to check your gimball bearing often, couplers and bell housings are nearly impossible to find. I recomend reading up on the manual and replacing the lower shift cable when they become too dificult to adjust. As for the engine, good thing it is a 454 and not a 460 (more impossible to find parts). engine parts are available for 454 from a aftermarket or gm source. As for the drive, a pressure test should indicate any leaks. have fun and be patient. These are good machines, however they recieved a bad rap from mechanics who were not trained specificly to work on them.

Click to expand...

Thanks for the info!

So it sounds like there's no way around taking this thing off and at least inspecting things from there? It was my understanding that this later style (similar to the Volvo SX) with cone clutch and the F-N-R gears up top, didn't have a lower shift cable?

Yeah in 1993 Donzi recalled all boats with the 460 and put the 454 in there. I'm not sure if it's the same block as it's cold as hell outside and I haven't had a chance to pop the valve covers to look at the head castings, but it has a holly 800, msd blaster, new stainless manifolds, etc.. so it's probably a new engine.

I looked up the forum threads on the pressure test, but not relating to the late model king cobras.. hmm.

Re: OMC "daddy" King Cobra - new owner, things to check?

TorchedGT said:

The boat was converted to thru-hull water pickup direct to engine water pump. I don't know much about this other than that some others complained of water flow problems with the king cobra also? Is this good or bad, and what will this change when I service stuff.

I'm most concerned about anything rubber.. Seals etc.. And the overall alignment of the drive. Should I take anything apart to check it? New fluids?

Also how can I check the shift adjustment on this guy?

I've got a manual coming in the mail but I'm curious if anyone has first hand experience.

Click to expand...

Howdy,


Well, I won't congratulate you on the purchase. You bought a boat with an obsolete drive that was only made for a few years. There are parts that are no longer available. So, when you rebuild the engine, you probably shouldn't "speed-tune" it too much. If you break it, you may not be able to get it rebuilt. The good thing is that you may be able to remove the drive and transom mount and replace it with a VP transom and DUO-Prop drive which will be a HUGE improvement in performance and reliability.

The previous owner installed a thru-hull water pickup and engine mounted raw water pump because you cannot buy raw water pump impellers for that drive any more. (Some old OMC dealers may still have old impellers collecting dust on their shelves. No manufacturer is currently making them) There are many other parts for the drive that are simply not available.

If it has an MSD "Blaster" and you have an MSD or similar distributor on it, then you're lucky.
It came with a Spitfire ignition system. No parts for them either and the only answer is to replace it with an after market distributor.

If you're going to try to do any maintenance on it you MUST get an OEM service manual for it. If you ordered an after market (NON-OMC) manual you might start looking the OEM manual now.

Yours is OMC's first attempt at a cone clutch drive. They developed them and a few years later partnered up with Volvo Penta. The result was the excellent OMC/VP SX Cobra. but there's little if any parts commonality between the first OMC cone clutch drives and the later VP/OMC SX drives.


Propping your drive is simple. Select a prop pitch that gives you the top of the recommended RPM range at WOT (wide-open-throttle)

I.E if your engine should turn 4200-4600 RPM at full throttle, prop it for 4600 RPM at WOT with the boat lightly loaded. This is the "standard" of the industry.

I'm most concerned about anything rubber.. Seals etc.. And the overall alignment of the drive. Should I take anything apart to check it? New fluids?

Click to expand...

You should probably closely inspect or replace the drive bellows. The drive will be off when you R&R the engine, Closely inspect the drive oil for water or other contamination.


I had an OMC 460 King Kobra in my 87 211 Four Winns Liberator. It wasn't pretty.

I fixed it by removing everything and replacing with a 97 Merc 454 Bravo.


Good luck,



Rick

HT32BSX115 said:

Re: OMC "daddy" King Cobra - new owner, things to check?



Howdy,


Well, I won't congratulate you on the purchase. You bought a boat with an obsolete drive that was only made for a few years. There are parts that are no longer available. So, when you rebuild the engine, you probably shouldn't "speed-tune" it too much. If you break it, you may not be able to get it rebuilt. The good thing is that you may be able to remove the drive and transom mount and replace it with a VP transom and DUO-Prop drive which will be a HUGE improvement in performance and reliability.

The previous owner installed a thru-hull water pickup and engine mounted raw water pump because you cannot buy raw water pump impellers for that drive any more. (Some old OMC dealers may still have old impellers collecting dust on their shelves. No manufacturer is currently making them) There are many other parts for the drive that are simply not available.

If it has an MSD "Blaster" and you have an MSD or similar distributor on it, then you're lucky.
It came with a Spitfire ignition system. No parts for them either and the only answer is to replace it with an after market distributor.

If you're going to try to do any maintenance on it you MUST get an OEM service manual for it. If you ordered an after market (NON-OMC) manual you might start looking the OEM manual now.

Yours is OMC's first attempt at a cone clutch drive. They developed them and a few years later partnered up with Volvo Penta. The result was the excellent OMC/VP SX Cobra. but there's little if any parts commonality between the first OMC cone clutch drives and the later VP/OMC SX drives.


Propping your drive is simple. Select a prop pitch that gives you the top of the recommended RPM range at WOT (wide-open-throttle)

I.E if your engine should turn 4200-4600 RPM at full throttle, prop it for 4600 RPM at WOT with the boat lightly loaded. This is the "standard" of the industry.



You should probably closely inspect or replace the drive bellows. The drive will be off when you R&R the engine, Closely inspect the drive oil for water or other contamination.


I had an OMC 460 King Kobra in my 87 211 Four Winns Liberator. It wasn't pretty.

I fixed it by removing everything and replacing with a 97 Merc 454 Bravo.


Good luck,



Rick

Click to expand...

Rick, I know this is a really really old post but I cant find any information at all on the OMC "Big Daddy" King Cobra outdrive. I have a 454 king cobra in my 90 Four Winns Liberator. This boat starting dieing out on lake about last 8 trips. I was thinking ignition failure because it would turn off after running like 10 mins. Then cool and start and run again good. But last trip out the gates it turned off In first mile.

We got it home and adjusted the ESA Electronic Shift Assist to specs, and it ran great for 10 mins before we shut it down for winter I noticed dark fluid in the dirt mixed in with the water and thought where is that from? This year we tried to start it and it would not turn over. Checked gear oil. Empty. Put more in it and it dripped out prop side.

Took the outdrive off and could not get driveshaft to turn and inch left and right while prop was locked up. Now I took the bolts off the lower unit to drop it to see what mangled up, and it wont drop. Its lose, swivals and inch, but wont drop more then a quarter of an inch. Any idea what hanging it up? I would like to see if I can fix it or find a used one somewhere. Cant find anything cheap. But I also would like more info on that Mercury Bravo conversion.