LAC_STS

As some background this 350 4 bolt main, 2 pc seal Im working on is/was a boat engine. It was leaking oil and lost oil pressure while underway. When it was shut off and when it was ran again it had a lower end knock.

I finally got around to tearing into it and what I found was oil on all spark plugs, a blown head gasket on both sides in between #3 and 5 and in between 4 and 6. All of the oil pan bolts were just on finger tight so thats why it was leaking oil. The main bearings looked just a little worn but the rod bearings were all pretty worn. #3 and 8 were worn very bad. Not spun yet just worn bad.

So I know I gotta fix all that. But my question involves the pistons/rings/block.
With the heads off, when I would turn the engine by hand I noticed on a couple of the cyl that when the piston would go down in the cyl I would wipe the cyl clean. But when it would come back up then back down it would leave oil in the cyl.

Now could this be from me having the engine upside down for a day or two? I already have all of the pistons out. The bores look clean and I cant feel any rough spots.

I'm taking the crank to a machine shop to have it turned and the rods and pistons too to have them checked and everything boiled.

Can I just replace the rings or do I really need to take the block and have it bored 30 over? Id rather not if I dont have to because it will add alot of expense to this. Im just rebuilding this to keep as a spare incase something happens to my new engine one day and I need it for a while to get me through a boating season.


Much thanks

pancherj

Is there a ridge at the top of the cylinders? If there is, the bores are most likely worn. Measure them and see where they are at. That will tell you if putting in new rings and honing the cylinders is acceptable.