I have a Cummins built 472 crate Hemi engine that I bought in 2005. I have never run it. I know that because of all the issues that these engines had, such as 528 head gaskets on a 472, improperly hardened Comp cams, valve seats falling out of heads etc, that I need to go through a 13k engine completely before I ever run it. My friends 472 Hemi had the rear main seal installed backwards when he fired it up right out of the crate. His second 472 lunched a cam after 6 hours of run time. I plan on a complete rebuild of my crate engine before I run it. I know that the current crate engines are much better quality than the Cummins built engines were, but I just bought a 70 Hemi short block, and I will be building my next Hemi myself from scratch. I would contact Indy Cylinder Head, and ask them if they know of this issue with the world blocks, and if they know of a fix for this. They buy and sell a lot of those blocks. Maybe you have an early world block and this issue may have been corrected.