I haven't been around an R40 but I do own an R50. If I were combining spring wheat, which I do a fair amount of, I would set as following: Fan - 6 to 6.5, sieve - open a good 3/8, I run an air chaffer, so no adjustment there, concave clearance can vary - I have had good results with a tight opening somewhere just over 3/8 but less than 1/2, or opening it up to at least 3/4 and keeping the rotor full, mind you you will get a little dirtier behind the machine after a turn until it fills up again, also your pacer will tell you that you are going too fast, you must push through it and then it will get it clean again and go back into the green, cylinder speed -800 to 850. Hope that helps.
Thanks for your suggested settings. I followed them, but have had to close the cylinder setting really tight, almost touching. Since my request on the forum, I've discovered that concaves are in bad shape. Previous owner must have ingested rocks, & this is no doubt the reason for the white heads.