Hi Sparky sorry to hear of your misfortune, do you have any pictures of the crack in the engine we can see and learn from?
These engines do need a long run in period I put 5 letters of 20:1 fuel through mine with 8 turns out on the low and 4 on the high, and not going above 4000 rpm on WOT (wide open throttle). They do need to be run very rich for the first few hours, I think my run in period totaled 3 hours of engine run time before I started to tune it.