Re: Converting an OMC King Cobra drive to the new Volvo Penta DP-S dual prop drive.
I don't see why someone would just off hand say that guy was a liar... The drives share more parts than you realize. The KC transom assembly was just a large SX for higher horsepower applications, the SX pivot housing would fit so why not the DP, the KC is the same bolt pattern transom with two extra bolts? Difference being that shifting and water hose sides are swapped... I don't see the difference between my KC pivot housing and that one concerning how far it sticks out. I'm also in Alaska right now and can't get a good pic. If memory serves me they use the same drive shaft
I'll tell you what gets me... and it ain't the dreaded your boat will blow up sink and kill your family and 10 of the closest families to the boat because you have a Cone KC haha. I took this thing in to have the upholstery repaired. Brought it to the wrong guy, waited 3.5 months and the boat looked like garbage, my wife and our friends took the boat out and the strap that was made for the engine cover didn't hold the cover down, it blew off and got run over... HAHA another 500 in the toilet and i haven't even gotten to ride in it since i pulled the OD last year!
Here is what I was talking about, you lost me with your response.
POSTED FROM A DONZI FORUM ELSEWHERE>>>>
I did some googling and found this on another forum, I was going to link but it's probably better to just quote the conversation here for future reference. I have to assume after reading this that it isn't exactly a plug and play operation for the lower either.
Converting an OMC King Cobra drive to the new Volvo Penta DP-S dual prop drive.
As many out there have asked for information about converting the OMC Cobra drives to the new Volvo Duo Prop drives, here it is. Having a customer that wanted to make the change on his boat, because it was about $12,000 to $15,000 cheaper than a complete repower, I thought I would write up the information on what was actually necessary to do the job.
This will be going into a Bayliner 2858 with a 460 Ford with Power steering.
Here is how it looks when complete.
Talking about it and actually doing it are 2 different things all together. There is no kit for a 460 Ford engine and no place to mount the raw water pump, and there was not enough grooves in the crankshaft pulley to add a raw water pump. Other than that, it looked pretty simple.
There are 2 kits that need to be ordered from Volvo, along with the drive of the correct gear ratio, and the correct size props.
The kit numbers are:
3857377-------Transom shield kit. All engines.
3857386 ------Water pump 3.0L Engine
3857380-------Water pump 4.3L Engine
3857384-------Water pump 5.0/5.7L Chevy Engines
3857382-------Water pump 5.0L/5.8L Ford Engines
There is no specific kit for the 460 Ford engine. I used the 3857382 kit with pump and bracket for this conversion.
Below is a picture showing the front of the engine with the old crankshaft pulley and powersteering pump removed. The plywood to the left of the tank has to be notched out for room to put in the new 3 groove pulleys ordered from
www.zoops.com. I also had to lift the engine up in order to get the hose for the shift cable moved to the proper location as it was impossible to remove the old cable or install the new style cable. so while the engine was up the plywood was cut for clearance. But, it was an additional 3 hours of work.
This shows how the raw water pump sits to run on the outside groove of the crankshaft pulley. The power steering pump now sits 1/2" closer to the engine block in order to fit the new 3 groove crankshaft pulley (below). As you can see there is very little room in front of the engine for all this extra stuff !
This is the Zoops 3 groove pulley, not picured is a 2 groove pulley needed because of the different diameters of the original pulleys and the new 3 groove. The old circulation pump pulley actually touched the crank pulley. The pulleys were about $130 each as I recall their website is
www.zoops.com.
This is a picture looking down in the engine room so you can see how the raw water pump is mounted. The belt for the raw water pump is above and below the Power steering pump pulley nose piece. It's a tight fit in there, but it will all fit.
This shows where the shift cables come in from the fly bridge and lower helm and go out to the outdrive with a single cable. The original OMC cable was replaced with a 7' Morse cable. You will need a minimun of 1-1/4" of throw on each side of neutral in order to shift the new drive. You can just get it with the new cable.
This shows how the new cable (Lower of the 3) is mounted
The parts I used for the installation other than a piece of 3/4" aluminum for a spacer are, and these are Volvo numbers:
3850266 Anchor
3852019 Retainer
3850941 Cable Adapter
Sorry, no picture yet of the new cable, but it's in and does work.I just forgot to take a picture of it.
Here you see the old OMC gimbal ring and transom shield with the new pivot housing installed. The kit came with new u-joint bellows and exhaust bellows. However, the kit was for a 5.8L and with the 460 we used the old exhaust bellows because it has extra reliefs cut into the bottom to prevent excessive back pressure and helps cut down on all the heat going through the drive.
There are also spacers installed inside the trim cylinders that prevent the drive from being trimmed down too far and breaking things. They must be installed, and it does take a special tool that is not included in the kit. Volvo dealers should already have this tool, It's the same tool used on the Volvo cylinders.
Ah Yes, the drive. Hanging on the drive hoist and ready to install.
After installing it, we found Volvo did not realize the pivot pin that goes through the trim rams and through the drive is 1/8" smaller in diameter than the OMC pin they said to use. That would beat the drive pin hole to death in very short order. They had no fix for it.
I was able to use a new Volvo pin and remove the plastic bushings from the trim cylinders and ream the hole with a 3/4" drill bit and the new pin fit perfectly. The new pin part numbers are as follows.
3857431 Pivot pin 1 needed
3857588 washers 2 needed
3857521 E ring 2 needed
3857522 caps 2 needed
Did the on water test today, smooth water, no wind. Tested with GPS for speed in MPH (averaged to and from because of current.) and boat has a FlowScan installed for GPH (Gallons pre hour)
WOT 4600 rpm, 38 MPH using 31.1 GPH
Cruising speed, just a comfortable sound and speed for the engine and boat was 3500 RPM, 27.6 MPH using18.2 GPH
At 3100 rpm was only doing 21.2 MPH using 17 GPH Don S
Ketchikan, Alaska
Edited by: Don S (
http://pub12.ezboard.com/bbocweb.sho...id=dons@bocweb) at: 11/6/03 6:15 am
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Converting OMC Cobra drive to Volvo DP-S drive. (Updated) Great Job and excellent pictures Don.
Do you know off hand whether this conversion would be possible to
a 1989 vintage regular Cobra drive ?? A friend has explored that idea with a SX drive as an update to his boat.
Tony
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Re: Converting OMC Cobra drive to Volvo DP-S drive. (Updated Yes, it's possible. Just different kits. If your friend is running a V6 or V8, go with the DuoProp if at all possible. The initial cost is higher, but the benifits are higher also. Don S
Ketchikan, Alaska
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Re: Converting OMC Cobra drive to Volvo DP-S drive. (Updated
Yes, it's possible. Just different kits. If your friend is running a V6 or V8, go with the DuoProp if at all possible. The initial cost is higher, but the benifits are higher also. Don S
Ketchikan, Alaska
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Thanks Tom
There was a few times when it looked like it just couldn't work. Impossible to find pulleys for the 460 was really the only real problem with the whole job. Mounting the pump wasn't a problem either.
On any other OMC engine besides the 460 this is a very easy job.
Don S
Ketchikan, Alaska
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Great Job Don
What was the cost of the conversion?
Steve
Ottawa, Ontario
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The pivot housing/drive joint has (seems to have?)less sealing surface than omc design that uses bellow's end to prevent water entering the bellows.The Volvo design seems to rely only on that paper seal.If it really is so,there seems to be a reason to consider using something slightly"gluish"stuff to help that seal.
I hope Volvo did not create a problem for those used to use only the seal with OMC design.I use grease with the seal,so that is maybe enough to stop the water...
Thank You Don S for giving hope to us Cobra owners.The possibility to use existing parts for repairs helps the resale value of OMC equipped boats.
Timo
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Re: seal
Steve
The invoice was for $11,340 USD. Parts, Labor, Outside work for brackets etc.
Timo
There is no gasket at all on the Volvo drive, just the seal ring around the water port and the bellows. The drive presses against the rubber bellows to prevent water from getting in. There is nothing else that needs sealed. All the other areas can be full of water with no problem.
Don S
Ketchikan, Alaska
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seal
Yippee!That ends the "to glue or not to glue"discussion
It after all seals like the OMC design at the bellows.
Timo
