Found this in my oil pan

[olddog]

Originally Posted by dcdoug

So I have the answer to these metal bits - main bearing #5 was about ready to go. Glad I pulled it. (I don't have pics, just spoke to the builder by phone as I was out of town). Some scoring on the cylinder walls, so will need a cleanup overbore.

Not to toot my own horn too loud, but clear back at post #10, I was pointing that direction. Although I later waffled on that after you said it was soft like a copper RTV, if I remember this correctly.

You already got advise from more knowledgeable folks than I, but I agree with 10:1 compression or less for cast iron heads. I wouldn't go over 10.5 with aluminum heads.

Although higher compression makes more power in theory, you can get into detonation problems. Then you have to pull timing out to stop the detonation or dump more fuel - maybe both. After that you can easily loose all the theoretical power the higher compression theoretically gave you, and sometime you loose more.

My brother in law was given a 406 SBC with 12.5 compression pistons that was intended to go into a alcohol race application. He dropped an RV cam in it and put it in his 2 ton dump truck. We had to pull so much timing and run so rich to keep it out of detonation that it was a fuel guzzling powerless dog. The stock 350 had way more power.