Any one have an opinion on how bad this piston looks? The rest are not this bad, but I guess I have to act on the worst case. What caused this? Can it be reused?

 

That's scuffing on the piston,usually from too much piston to cylinder clearances.How do the cylinder walls look on the block? I would take the block to a machine shop,have them clean the block and check the cylinder bores ,could be tapered,out of round,etc.

 

To tight, or bad fuel/oil mix...... i'd buy a new set

 

I would agree, either too close of tolerance or possibly an oiling problem. I would replace them after making sure the block is good (good round holes the right size and clear oil passages.

 

What tolerance range is aceptable? The block looks scuffed, kind of what you would probably expect from the piston, only not quite as bad, I guess the aluminum piston is softer.

 

Just from a quick look on the internet, for a 360 it looks like .0005 to 0015 according to this web page:

http://www.angelfire.com/ca/mikesspot/360specs.html

 

You will need to hone the cylinder at least. Take some measurements of it to make sure that you do not need to bore it out. Do that before buying in piston(s).

 

I should be dropping off the block in a week or 2. I will measure the pistons and take it from there. Thanks again.