My EIII is identical to a K, only 4 cyl D17 engine. For barley, you need to tighten the cylinder to nothing, zero, tight as possible. You control cracking by cyl. speed. This should end the heads in the seive.(there shouldn't be any back there other than small partial heads)) Remember, the cylinder does All the threshing, not the cleaning area at the back of the combine. Hope this is helpful.