http://fordcustoms.com/photopost/data/508/P1010039.JPG This is a link to a picture of a piston I chiseled out of a C2AE block two days ago. Just curious as to how long it might have run with this kind of damage. What do you think? Everything was non salvageable, except the rods may be good. Block had sat outside unprotected without heads for a long time. Ring pieces were in the oil pan, beneath the water.

 

The broken lands were that way when you pulled it? Is it the original bore size?

 

Yes they were that way. If you look closely in the picture, and click on it for the large size, you can make out the ends of the broken lands which have been ground to a blunt point, I assume by the action of ring fragments moving up and down with the piston. The pistons were .040 over, and there was at least .030 of damage to the cylinder walls from rust, plus whatever the taper wear was, which couldnt be measured.
This piston with rod came out a little easier than some of the others. I could see some of the damage as I was working on it from the inside of the cylinder.

 

Hard to tell, but my guess would be, with a rebuild, that either the ring end clearance was set too tight, side clearance was too tight, or, possibly, the ring was twisted during installation & broke shortly thereafter. Run for a good while, I'm thinkin.

Block's junk? Might be your opportunity to build a BIG Bore Y....get one of those 312 cranks made from un-obtanium.