Engine carnage, Incorrect clearance Options

[nine14cats]

As many of you know I missed a shift earlier this year and blew up my 2.7L 6 at Buttonwillow. I'm currently building a new car with a 3.6. I sold my burned up motor to a raceshop and they tore down the engine. What they found was that I did not bend valves as suspected. I broke the rings on every cylinder due to incorrect head clearance.

My missed shift was going to do damage, but not this much if the machine shop I used had done the clearancing correctly. What is interesting is that on the last rebuild I did with this engine, I used a large, nationally know engine machine shop and thought I was safe.

Even if I didn't miss a shift, my engine was living on borrowed time. It appears the pistons and heads were touching. It kinda makes me lose faith in everyone I talk to in this business. I'm not a master mechanic, but the lack of of attention to detail I have run across over the past 2 years has been really disappointing. Maybe I'm just cursed.

Anyway...here's some pics of what happens when your P's hit the heads.

Bill P.

[Demick]

I don't get it. The pistons and heads were touching? How can they make a mistake like this? The only way to build and engine and set the compression ratio is to measure deck height and CC the heads. How can a shop measure all this and then set the engine up so that the pistons touch the heads? That's a huge f-up.

You sure it couldn't have been that the top ring gap was simply set too tight and the rings butted. The over-rev then fractured the butted rings? Just guessing.

Demick