Got some better pictures of the carnage:











Thankfully, the bore looks just fine (the piston, not so much)







Better picture of the debris I plucked out of the head:

 

Not so bad looking. A little filing, sanding, and you should be good to go. Can't tell how deep the gouges are in the piston, but if they are superficial with no cracks, then you didn't do structural damage. Luckily you had a small piece in there. A bolt or nut would have likely put a hole in the piston.

 

The gouges in the piston are pretty bad, just as bad (if not worse) than the head. The piston definitely needs replaced.

 

The head is no big deal though, those dings aren't going to hurt anything by being there. I would just file the high spots off and sand it smoother so you don't create any possible carbon built hot spots.

 

Well the whole head really should be machined. The impacts created an indentation near the water jacket, which is what caused coolant to get into the cylinder to begin with.

 

This is not my understanding. Do you have an links explaining this? The oil plays almost no part in the damage. The Glycol part of the antifreeze breaks down into a acid. The only way the oil would have an effect would be if it was a base that neutralized the acid.

 

The way I was taught was even a single nick is bad. I think GM said under .015” was acceptable but that is for mom’s minivan. For a performance engine you really don’t want any. The gouges cause stress risers and heat risers.

A stress riser is any odd shape geometry that affects the way stress spreads out through a part. They tend to be where cracks start. Even micro defects can cause stress risers. This is why we polish the tops of pistons and connecting rods in race engines.

Heat risers are cause by odd shape geometry that affects how the heat spreads out. Heat moves much like sound with a gouge you are remove 50%+ of the materials ability to flow heat from the edge. This means the edge of the gouge cools slower. If the edges get hot enough they will cause pre-ignition. (The edges will ignite the gas before the spark plug). Your knock sensor would detect this and retard the time enough to cool the cylinder resulting in a loose of HP.

If you had coolant in the oil you should just start with a different LT1 and rebuild that or find a low miles engine and reseal it. If you have to use this motor each nick should be polished to a dish shape to avoid heat and stress risers
Good luck.

 

The plan right now is to remove the engine, replace the piston, and see if I can get that head repaired by a machine shop.

 

look around, lt1 heads are not that expensive. LT1 Heads | eBay

 

If the head was stock, I would just get a replacement. But these heads have been custom ported, so I'd rather not throw either of them out if I can help it.