Combines 1680 settings for spring wheat

Are the bars on the concaves rounded offIJ As they become worn, it is more difficult to get the wheat threshed. I would start by covering the first concave. That will help compensate for some wear. Slowing the vanes down might help a little, but in my experience it mainly just wastes a lot of HP. How much return are you runningIJ If it is full, you may not be getting all of it returned to the rotor. Take the panel off on the right side and feel the top of the cross auger that returns the grain to the rotor. The top of it will be cut out, which allows unthreshed grain to bubble out and skip the rotor. We install a piece of tin or a chunk of old 6" auger tube to this area with a big hose clamp. Then, the return always gets threshed again. Check the front of the rotor and make sure all the rotor bars are installed. Some folks take a few of the short bars off for certain crops, but you will want them all installed for wheat. If you see bare mounts, you will know some bars are missing. If you are not cracking too much grain, I would set the rotor speed at max (over 1000 rpm). I would also zero the concaves out and check the pinch point. You will probably need to run the concave clearance tight, but not clear down to zero. Crank the fan speed up until you loose some grain out the back, then back it down. If you don't have the fan deflector, you may be able to run the fan near max speedIJ How much chaff do you have in the return and the binIJ

Farm kid2 has great advice. In oregon we have same prob. with spring wheat. I blank entire front two concaves. Run transport vanes in fast over concaves and slow over sep grates. Keystock grates are great help. Also rear axle position makes lots of difference. run axle in low holes. This puts rotor and chaffer at steeper angle, now grain will stay in combine an extra shake or two. I got sick of the complete joke of a return on the IH, so I built my own which has three times capacity and wont ever plug. Runs all return to the feederhouse. In good conditions its just there, but in poor conditions or for small seed like clovers it has been invaluable.