L/U Casing # 1647 6670 vs 1647 6670C

[w2much]

i am trying still to identify this lower unit casing so that I may purchase parts for it. I have found 1647 6670C as belonging to a 150 HP Merc but I have not seen / found 1647 6670 . Would these two sets of numbers be the same lower unit casing. I purchased a 1979 200HP 2 stroke Merc with this (1647 6670 ) casing on it. It is the C which is throwing me off, I dont know if this lower has the original parts in it or if it was just put together with spare parts. I would certainly appreciate any info any person may put forward. Thank you.

 

[Chris1956]

Gears, bearings and the like are fairly expensive, and take special tools and knowledge to install. Have you priced a replacement gearcase from SEI? It could be close in cost to the parts you need.

 

[w2much]

You are correct and I agree although for me it is not the way to go. I appreciate your suggestion. For better or worse I plan to forge ahead in my folly. Fools rush in.................. . Mercury parts listing are a bit confusing as there are different lowers for the same engine model and years. I just need to be certain that I am ordering the same parts for the same lower casing I have. A lot of parts numbers have changed or show obsolete when in fact I may have some of them or be able to use some obsolete part numbers which are new old stock.

 

[Faztbullet]

Your unit if original will be a pin shift like a Inline outboard. The (c) casting my be for a desmodromic shift as change in 1980

 

[w2much]

Your unit if original will be a pin shift like a Inline outboard. The (c) casting my be for a desmodromic shift as change in 1980

 

[w2much]

Got me on what is a desmodronic shift ? I am pretty sure that the lower unit has been switched. From what I can tell. I am working with a lower from a 1978 to 1986 serial 4868988 - A904645 without a driveshaft nut. So yes, I am confused again. Why does the diagram show a driveshaft nut? I am assuming it refers to the nut under the pinion gear. I hate assuming . Also the pin and spring are missing on the driveshaft. How do I replace it ?

 

[Faztbullet]

post some pic of what ypu got...end of prop shaft that has shifting parts

 

[w2much]

No need to post pictures but thanks for offering to help me identify my lower unit. I found my lower to be called Torpedo. I am not certain it is the original but I now have the diagrams needed to continue. I am working on a 175HP 2 stroke carbureted 2:1 Ratio - 14 Teeth Pinion Gear (1) serial 4301235 to OC100860. It all makes sense to me now. My thought was that the PO had just taken parts from different lowers and somehow had gotten it to work. I was thinking the PO was either really good or really bad in order to figure out how to do this . I am amazed at how many different configurations there are to Mercury lower units. The way the diagrams are presented and corresponding parts are designated to specific cases scrambled my brain. I can see moving forward will be an ongoing learning experience . I have fabricated a few of the tools needed and will either purchase or make the rest. There will be questions coming up no doubt and I always appreciate the replies . On that subject can the pin and spring be replaced on the driveshaft ? If so how ? Thanks again for your help.

 

[Faztbullet]

That why you need to post pictures. The unit with nut refers to spanner nut that holds driveshaft and bearing in place. Also there is not a model called Torpedo, that just refers to shape.

 

[Faztbullet]

Does inside you case look like this?


And prop shaft like this?

 

[w2much]

Yes that would be it. Roger on the Torpedo. I have been using an other than factory manual until today. The lower unit has beed identified a day before my Mercury manual arrived. i cant put it down. Thanks