Help with OMC identification

[gilliac]

I bought an old Donzi with a GM 350 and an ancient OMC drive. The hull is good and my first plan was to replace the whole package with a 5.7 MPI and a Bravo drive. BUT a friend says that since this OMC drive has the water pump mounted on the top rear of the drive (under a cover) that this is a "cone clutch" style drive which is worth rebuilding and will easily handle the 300 MPI engine.

The paperwork on the boat says it is an 89 and what I read on the net says the cone clutch OMCs did not ship until late 1990. Before I lose a good deal on a 5.7/B3 package, I need to decide what to do with this drive. Does the top mounted water pump definitively mark this as a cone clutch style? An if so, are these drives dependable?

The boat is a 25 ft cabin cruiser and the hull is solid. With a new engine and a good drive it will make a great dive/fishing boat for the Gulf. But I don't need to sink a lot of money into the OMC just to replace it later anyway.

Any OMC experts still around?

Thanks

Gil

 

[gilliac]

Re: Help with OMC identification

Never mind - I got it apart and it is a dog clutch standard Cobra drive. At least the only transom work is drilling two more bolt holes for the Bravo!

I will wait till summer and post the OMC parts on eBay.

Gil

 

[bruceb58]

Re: Help with OMC identification

Be glad its not the cone clutch Cobra. That is if you were going to keep it.

 

[Lou C]

Re: Help with OMC identification

You can also switch it over to a Volvo SX without having to replace the entire transom assembly and pull the engine....you replace the pivot housing with the Volvo part, and add an engine mounted impeller, spacers for the trim rams....a lot less work, unless you have to pull the engine or the transom mount is in bad shape.
BTW, if I could get a good rebuilt Cobra (dog clutch) as a spare for my boat, I'd have no problem sticking with it. When you know how to set them up they last a LONG...TIME....my original one....is 26 years old....no major drive work at all....

 

[gilliac]

Re: Help with OMC identification

Bruce and Lou - thanks for the replies. I am 100% ignorant on the Volvo drives (only 90% on Mercruisers!) so can I bother you guys for a little info?
On the comment about being glad it wasn't a cone clutch OMC, is this because of poor design/reliability or just hard to get parts? Just curious.
On the swap to a Volvo SX, is the stern cutout the same on an SX and whatever the dual prop Volvo is called the same? The reason I ask, is the more I work on this old Donzi, it seems to be built like a tank and the hull is solid. I only have about three grand in the boat and trailer but I am considering spending the money for a new powertrain. Something like this new would be 50K plus. I think I can replace the engine/drive and electronics for less than 20K and have a great boat. Obviously it would be to keep as resale wouldn't bring much on a twenty five year old boat!
But if I do go all out, I want a dual prop and closed cooling so it looks like either a full VP or MC package. I understand the Cobra drive cutout is the same for the MC Alpha and I just drill two more bolts for the Bravo. I have no idea of what is necessary to fit a dual prop Volvo.
Thanks
Gil

 

[bruceb58]

Re: Help with OMC identification

The cone clutch Cobra is VERY hard to find parts for. One example is the raw pump impeller. MANY parts are no longer available.

SX and Duo prop Volvos are exactly the same except for the lower unit. Stern cutout is the same. I don't know if the transom assembly is the same so someone else has to comment on that.

If your choices are between a Volvo and a Merc Alpha, go with Volvo. Tossup between Volvo and Merc with slight nod to Volvo because I am biased.

 

[Lou C]

Re: Help with OMC identification

The best way to go depends on what you have access to. If you can get a whole Bravo engine/drive package for the right price and you know how to maintain it, go with that. I mentioned the Volvo conversion because it can save a lot if work if the Cobra transom mount is in good shape. The reason why a Volvo can be fitted to a Cobra transom mount is this: in 94 OMC and Volvo went into a joint venture. The Cobra was redesigned to use cone clutch shifting. The new drive was sold as the OMC Cobra and Volvo SX and they were the same. The Volvo DP had the same upper unit and a DP lower. It can be expensive to find a good Volvo drive but they are very good. I stuck with the Cobra because I found it to be a well engineered and very durable product. The bad rep was caused by defective shift cables and a lack of proper training on how to adjust them. When you have the 3 OMC tools and the correct instructions it is not hard at all. My 26 year old shifts great and has not needed any major repairs. This boat is used in salt water and sits on a mooring 6 months out of the year.