Combines Corn Chaffers

I have an older long square tooth chaffer that I had to modify myself. The front rows are now open a little more (I dont know how much exactly) than the rest of the chaffer. Thats what everyone on this board recommended a few years ago. Tom in MN

With the long shoe it changed the air flow so that there is a lower air flow in that area so they want it tighter there, The higher air pressure is just after the tighter rows.