Hello,
Ok, first a little background. I have a '78 Harris Flote Boat with a '77 OMC 120 Sterndrive (model #990234E). I got the boat for cheap cheap last year and have only had it out a couple of times. Long story short, the block has 2 cracks, one has been previously welded, the other has not. There is water coming from the one that has not been welded (but no water in the oil). The manifold also has had a crack welded, and is full of rust. Compression test showed ~65psi across all cylinders. I did manage to have the engine running last week before I discovered the cracks, but it only was only running on 2 cylinders. Basically, this engine is toast.
Locally, I have not really had any luck finding an OMC 120/140. However, I have found an '83 Mercruiser 120 for $200. I plan on looking at it tomorrow evening. The only catch is that it does not have an outdrive.
Now, my question is this; would I be able to use the block from the Mercruiser and bolt it onto the OMC mounts and bell housing? Would I need an adapter of some sort? Different flywheel? I'm not too concerned about the engine mounting brackets, as those are easy enough to fabricate if need be, I'm curious as to where the standard GM motor stops, and the OMC/ Mercruiser starts. Is there any kind of a cross reference that shows what will interchange between these motors? I've searched these forums and others and haven't found a clear cut answer.
So, what would you recommend I do? Try and repair the OMC, use the Mercruiser block and try to fit it to the OMC outdrive, find a Mercruiser outdrive to go with the engine, or spend more time to find a good OMC long block?
I know that it would probably be a pain to mate the Merc with the OMC, and that I will probably have to run new cables and wiring. I only want to spend about $600 on this right now. And trust me, I am trying to find an OMC, but good ones are few and far between.
Ok, first a little background. I have a '78 Harris Flote Boat with a '77 OMC 120 Sterndrive (model #990234E). I got the boat for cheap cheap last year and have only had it out a couple of times. Long story short, the block has 2 cracks, one has been previously welded, the other has not. There is water coming from the one that has not been welded (but no water in the oil). The manifold also has had a crack welded, and is full of rust. Compression test showed ~65psi across all cylinders. I did manage to have the engine running last week before I discovered the cracks, but it only was only running on 2 cylinders. Basically, this engine is toast.
Locally, I have not really had any luck finding an OMC 120/140. However, I have found an '83 Mercruiser 120 for $200. I plan on looking at it tomorrow evening. The only catch is that it does not have an outdrive.
Now, my question is this; would I be able to use the block from the Mercruiser and bolt it onto the OMC mounts and bell housing? Would I need an adapter of some sort? Different flywheel? I'm not too concerned about the engine mounting brackets, as those are easy enough to fabricate if need be, I'm curious as to where the standard GM motor stops, and the OMC/ Mercruiser starts. Is there any kind of a cross reference that shows what will interchange between these motors? I've searched these forums and others and haven't found a clear cut answer.
So, what would you recommend I do? Try and repair the OMC, use the Mercruiser block and try to fit it to the OMC outdrive, find a Mercruiser outdrive to go with the engine, or spend more time to find a good OMC long block?
I know that it would probably be a pain to mate the Merc with the OMC, and that I will probably have to run new cables and wiring. I only want to spend about $600 on this right now. And trust me, I am trying to find an OMC, but good ones are few and far between.
. Speaking of which, any tips or tricks on a motor swap?