Converting 1988 OMC King Cobra to Volvo Penta DP-S

[paulcierra26]

I found a write up of a person who did the conversion using the exisitng 460 King Cobra power , he swapped out the old King Cobra Leg for a Volvo Penta DP-S . There was defiinitely some issues like mounting the water pump , new shift cable but judging from the write up it sure looked doable.

Looking back at some old post it sounds like it might have been Don? one of the moderators of this forum that actually did the conversion for a customer of his.

Don, if you happen to read this and you are the one , I would like to ask you how you changed the shift cable routing ? The picture in the write up shows the shift cable now coming thru the lower bellows ready to mate to the Penta Leg. The old (original) shift cable does not run like this rather it has its own dedicated hole thru the existing transom shield.
I know fromthe write-up that a Transom Shield Kit is required, maybe with the kit comes the answer on shift cable routing?.

The boat that was converted in the write up was a Bayliner 2858 with 460 motor and King Cobra leg but the year of the original drive wasn't given , maybe its different than mine.

Mine is 1988 460 with a Dog Clutch, King Cobra Leg, confirmed as it holds 108oz of oil.
The leg I have to replace the old King Cobra is a Penta DP-S that came off burnt boat that had a GM Big Block, The boat was a 28ft and mine is a 26ft.

Thanks
Paul

 

[HT32BSX115]

Re: Converting 1988 OMC King Cobra to Volvo Penta DP-S

Hi Paul,,


I know what you're going thru having already done it!

Don did post a complete procedure here sometime back and I do have a copy of it somewhere.......I just don't know where.

He'll see this I'm sure.

There is an adapter or (Volvo) kit that is required I believe that allows you to do it......I think you do retain the original coupler and manifolds though.

So you would still spend a fair amount of money on the conversion and still have the risk of the other non-replaceable parts being unavailable or extremely difficult to obtain.


Since you do have a DPS drive. I'm assuming that it's in good shape and probably worth quite a bit. (when it was all said and done, I recovered a little over $3000 selling all my 460/king Cobra stuff..................I paid $5000 for the complete prop-to steering wheel 97 Mercruiser 454/Bravo III 4 years ago.)

You might still at least look into finding a BBC Volvo (or Mercruiser) engine and complete Volvo transom/gimbal etc to replace the Cobra stuff.

Also look for a similar Bravo engine/gimbal etc.

I still think staying with the 460 is not in your best long term interests....


Good luck!


Rick

 

[Don S]

Re: Converting 1988 OMC King Cobra to Volvo Penta DP-S

Here is the file from when I changed one over. I've done it to two of them, but that was back when couplers and exhaust manifolds and risers still existed.

http://www.4shared.com/file/242586082/8ac7f9cf/OMC_KC_to_Volvo_DP_Conversion.html

 

[HT32BSX115]

Re: Converting 1988 OMC King Cobra to Volvo Penta DP-S

Hey Paul,


I found a link for the OMC-Cobra "Kit"

http://www.marinepartsexpress.com/SX_Cobra.pdf

http://www.marinepartsexpress.com/cobraconversion.htm

http://www.marinepartsexpress.com:8080/mpeCart/details.faces?productId=3857377


I simply used the part numbers that Don supplied.....


Aside from the non-existent manifolds and coupler it looks "doable".


My guess is your main parts cost will be the Approx $900 for the transom shield, $400 for the raw water pump. $unknown fabrication costs to mount the raw water pump. couple hundred for fab cost for another pulley to run it.......cables, controls, You'll remove your ESA.

I would guest-imate maybe $1500-1800 for the whole job (if those Marine Parts Express prices are valid.......) That sound reasonable Don?

 

[paulcierra26]

Re: Converting 1988 OMC King Cobra to Volvo Penta DP-S

Thankyou all for the write up, it was the same one I found.

If you coud just confirm that the year of the ones you did was of the same vintage/type as mine , I shall bother you all no more.

Mine is the 1988 King Cobra , Dog Clutch Style that holds 108oz of fluid.

I just took off my old Transom Shield and the six mounting bolt holes match up perfectly to my new DP-S leg. Looks pretty uncouraging. The tag on the Penta Leg says 1:78 Ratio.

Thanks again

Paul

 

[Don S]

Re: Converting 1988 OMC King Cobra to Volvo Penta DP-S

Mine is the 1988 King Cobra , Dog Clutch Style

That's what I took off that Bayliner. It was an 87 I think.

 

[HT32BSX115]

Re: Converting 1988 OMC King Cobra to Volvo Penta DP-S

I also found the following on ebay. Exhaust manifolds from Doug Russell.

I don't know if they're new (old-stock) or if someone is actually making them again. Not cheap though! About $1500 for the pair shipped.

If you had to, you could do the modification for the coupler that someone does by machining the flywheel to accept a different coupler.

Before I pulled out all my "stuff" I tried to buy manifolds and it was no-go..... There were no coupler options then either...


Good luck to you on this.... You are going to LOVE the way that DPS pushes your boat!!

You may have to play with the props a bit. up or down. The 460 wants to turn about 4800 at WOT if I remember correctly.......... (My brother routinely ran it at 5000.......that's probably why it had a flat camshaft when I got it!! )


By the way, you can also "part-out" your King Kobra drive. There's a few parts that the rebuilders want because they cannot be bought at any price.

I think the common stuff like seals, gaskets, shims and some of the gears and bearings are still available but the case and vertical shaft are not...


Cheers,


Rick

 

[paulcierra26]

Re: Converting 1988 OMC King Cobra to Volvo Penta DP-S

Thanks again all!!, I will take pictures throughout my changeover and do a little write up on how it all went for anyone else that may be contimplating doing the same .

For anyone else doing this, I compared prices between "MarinePartsExpress, Boats Unlimited and Discount Marine Products.

Shop around, the price varies.

I got everything from Dons list forapprox $1100
The most expensive supplier was over $1300 for the exact same parts.

Paul