Re: OMC Sterndrive
I think you are right its a Frankenstein. The boat was home built so it makes sense that they might have put the whole thing together with bits and pieces. I have always thought it was a old GM engine perhaps from a car. There are quite a few unconnected hoses etc. I'm not up on the mechanics of it enough to know what does what.
To get this thing to run right, and more importantly be safe, you're best off familiarizing your self with what's what.
To start off, you should look for a factory service manual that at least covers an engine like what would have come with that drive. Some of the OMC guru's may have suggestions on which one would work.
Take some detailed photo's of the distributor, carburetor, alternator, starter, fuel pump, and post them up here. To minimize any risk of explosion from fuel leaks/vapor, these should all be marine rated, and chances are high that if this engine was swapped out of a car, the bit's I mentioned may also be from a car, and not up to the task.
Your current cooling system, IMHO is risky. There are some people who will remove the circulating pump from their engine, and trust the impeller to both draw, and circulate the water, but I personally wouldn't trust it. You run great risk of localized overheating in the engine (something a temp gauge may not tell you), which can damage individual cylinders. It may cost some $$$ to get it back to what the factory intended for a cooling system, but personally I wouldn't take the boat out any distance (especially in open water) with out the cooling system being up to snuff.
As we've also seen in your photo, an EGR valve used to control NOx emissions in a car has no place on a boat. It can be disconnected and removed if you can fashion a block-off plate for the opening, or you could leave it in place (disconnected) to cover the passages for now. If the intake is aluminum (which it doesn't look to be by the photo), and you're running it in salt, you are going to want to change it over to an iron intake, or jacketed aluminum intake in the future.
I'll offer again, if you want to know what this engine is, and where came from, post the casting numbers and suffix code (if you can find one), and I can look it up for you. You may need to wire brush the little tab at the front of the left deck surface on the engine in order to read the suffix code if it hasn't been milled off by a machine shop.
