273 guys..Heads up!!!!

the gasket is larger than the bore and larger than the chamber. As i said in the thread when we were building our 273 we wanted a stock bore gasket but to none avail. what this means is ALL of your gasket is squished, the reason the big bore gasets suck is you have this nice sharp edge to get hot and a big gap all the way around the bore edge to collect junk like carbon.

Your problem is more than likely you had a ring end gap wrong and you broke the top of the piston off...