Omc cobra 5.0 gear set

[Dalton96]

I have a 4 winns boat with an omc cobra i/o 8 cylinder 5 0 motor in it. Im not positive on the year or brad of motor but I had the upper gears go out on me I believe due to a faulty water pump seal. It had 21:18 gears in it and new gears are around $600 so im trying to avoid that but I found some second hand ones that are 21:16. From my research those are meant for a 5.7. Can I use them for my 5.0? Do I need a specific prop? Is it going to cause excessive wear? Any help would be greatly appreciated.

 

[alldodge]

Welcome
Don't know about the OMC but with a Merc the gears can be swapped so long as they are done as a set. Changing ratios to a higher ratio set will normally need a lower pitch prop

 

[Lou C]

If doing a rebuild & you can get new OEM always go new. Used could have hidden impact damage that will come apart later. Doing a rebuild 2x is false economy!

 

[dubs283]

If doing a rebuild & you can get new OEM always go new.

Do you have access to new oem cobra gearsets?

 

[Lou C]

There is a company called Red Rhino parts that makes some parts for Cobras. I haven’t specifically looked for those but there are rebuilders who use them like Crowley Marine. Used is tempting but risky I think.
That’s the main problem with these units; they are very good when built right & maintained properly but when you need something major it can be difficult to find quality parts.
Other options are convert to a Volvo SX ($$$) or that SEI conversion (SEI drives have mixed reviews but no reason why you couldn’t use a genuine Merc Alphs drive with their kit).

 

[Lou C]

Omc Cobra Rebuild Kit for sale | eBay

Get the best deals for Omc Cobra Rebuild Kit at eBay.com. We have a great online selection at the lowest prices with Fast & Free shipping on many items!

www.ebay.com

I think these are the parts used by several major rebuilders. Can't comment on quality because I have no direct experience.
I do know that buying used units off ebay is a crap shoot.