Coolant leaking into 318 cylinder 8
So, the old block is no good because it’s .060 over……..but you’re boring the replacement block .060 over, so you can reuse the pistons.
I have no faith in this block because I do not assume what caused the crack. I definitely do not assume they bored the cylinder holes too thin. For all I know it was frozen, or otherwise stressed, and other problems simply have not shown up yet. If the remanufacturer missed one defect, how many others are barely hidden? The coolant system was not even pressurized. It has never been fired, never been warm, never had coolant pressure. And already had a hole leaking into a cylinder. .060" over bore is very common on 318s. Sure, there are probably some blocks out there too thin to handle it. Some guys have gone to a 4" bore on 318 blocks.
Honestly, the question is not why would I scrap it. The question is, why would I trust it?
Also, this is a 1984 block. It appears they used less metal. 9 of the 10 head studs are wet holes on this block. None of them are wet on the 67 block. Unless someone drilled all the head studs through to the water jacket, this seems to be a block with less metal in it.
The cost to sleeve one cylinder, then bore it, hone it, check the adjacent cylinder and possibly have to clean it up, then deck the block again, is not going to be cheap. It is not going to save me a ton of cash over machining an entire block. It is a nominal cost savings to risk finding other issues with the block. And I will have the block sonic tested before it is bored. If I have to buy pistons, I have a brand new unused set of .060 pistons I can sell, and recoup a little cash.