Well my much troubled 451 ended its career two weeks ago. Got on the freeway, and she began misfiring. Looked in the mirror and I couldn't see behind me the coolant was going out the exhaust so bad. Wrecker ride to the garage where I get it worked on. After sitting a day, the oil became overfull. Pulled the heads and found what you see in the pics: From what we can tell so far, I broke a piston and in turn broke the block. Consulted a good machine shop, and will have the heads inspected for reuse. Owner looked at pics and knew right away what happened. The ring gap on the top rings was insufficient for a Keith Black piston, and it expanded and broke out the ring land you see in the pic. A year ago, when I broke one of my built iron heads we'd found that one of the rods hadn't been resized and the bearing was getting ready to spin. We rectified that With new bearings and resizing of the rod, but even then on start up I had to crank for a few seconds before I activated the choke so that you wouldn't hear rod slap on start up. In addition, the engine always made a "wah wah wah wah" sound until it was completely warmed up. In short, my machinist was a crook stealing from his business, his customers, and doing shoddy work. I got screwed. So now here I am with really bad choices. I can sleeve the bad bore, and have a new shop check all the clearances and fix whatever is still screwed. Or, I can put a low mile RV 440 in, utilize the 440 Source heads, my oil pump, water pump, and XE268H Comp cam and runs that. That's probably my best choice as I don't trust that 400 block anymore, but compared to the 451 this 440 will be a slug. Last option, walk away from the car and sell it for whatever I can get for it. I can't afford to rebuild engines once a year. This sucks.