[lunaticeh]

Seeing as you say this engine sat for a while before being fully assembled and fired, did you remember to prime the engine before firing? Depending on what the builder used for assembly lube, it might be possible that not much of it was left. When I worked for a local machinist, if a customer came to pick up an engine that had sat for an exteneded period of time, short or long block, the pan was usually taken off again, caps pulled, re-lubed and re-torqued. After numerous cases of blown up engines, the owner purchased a dyno and now a short break in on the dyno is mandatory for all engines that leave the shop. Suprisingly the number of blown up ones coming back has dramtically dropped. Like some people have said, you might not ever know the answer as to why this thing cratered and the reasons are endless. If it hasen't been torn down yet I wouldn't be guessing at a problem. Wait till it stares you in the face, then see where you and your machinsist have to go from there. Good luck...