[76GMC1500]

That's a microseizure tansitioning to a full on seizure. *The metal on the cylinder is obviously aluminum from the piston being transferred to the cylinder wall. *Microseizures are generally caused by lack of lubrication, but can be caused by overheating. *Overheating localized to one cylinder is caused by lean fuel/air ratios, detonation, and advanced ignition timing. *This is a carbureted motor where oil is mixed in the carb? *I will say that the problem was caused by the carubretor. *If you do plan to reuse these carbs, REBUILD the one from the bad cylinder and have the others checked out before installing them on a new motor or you could end up in the same position.

Now, you want to get back on the water for cheap? *You have here what is a mostly good motor short of one cylinder and one carburetor. *How mechanically inclined are you? *You could strip the motor down to a bare block and take the block to the best machine shop in town. *You will get the best rates at an automotive machine shop, the process is the same regardless of application. *Any hotrod shop that deals with newer engines will be the best. *To sleeve a cast iron engine block, parts and labor come to $90 per cylinder. *Of course, your engine being an aluminum cast in liner engine can add some complicatoin and can add a little to the price of labor and the liner cost is going to be sky high. *If the liner is thick enough, they can just bore inside of the liner and install a sleeve just like on an iron block. *If the liner is thin, they have to bore the old liner completely out and start from scratch. *This is a little more costly. *For the best deal on a replacement piston, go to Wiseco. *They make drop in replacement pistons for a lot of engines. *If the failure is lubrication related, *you may want to replace the adjacent main bearings and connecting rod big end bearing. *You will certainly want to replace the connecting rod small end bearing as there is a good chance it was overheated. *Your wrist pin will probably come out blue and gold from the heat.

On further examination, I take back what I say about lubrication related. *That is definately an overheat failure. *Lubrication microseizures take place low in the cylinder where the piston skirt transmitts connecting rod thrust to the side of the cylinder. *The majority of the material is located at the top of the cylinder where the piston shouldn't make contact with the cylinder wall. *What appears to have happend to me is that your piston ring failed (causing the low compression readings you got earlier in the season). *The failed piston ring allowed combustion gasses to blow past the piston and heat it up to the point of seizure. *I feel confident in telling you that your ring failed because if it were still intact, it would have scuffed much of the aluminum deposits off of the cylinder wall.