Let's take a build craft tank for example, it is not given an emc value because some glass items that CAN be used to craft it don't have emc values. Prehapse ignore those?

It does, if you check the algorithm. This has to do with items belonging to more than one OreDictionary entry and those entries having disparate items in them. OreDictionary items are not always equivalent so there is some special casing there.

It's part of a problem with ExtraUtils that I still need to sort out.

Duplicate of #829