Combines spongy cobbs

Try opening up your concave clearance. One and a half is too tight. leave your rotor speed where it is and just start opening up your concave clearance up a little at a time. You will have a lot more loss when the cob splits than when it breaks in half.

How wet is corn, is your drum all the way up in feeder, is chopper in slow speed plus knives removed, maybe try open concaves alittle more and if that doesnot work try about 350 roter and play with cocaves open and closed and fine tune your seives.

What is the corn yieldingIJ 1.5 seems a little tight on the concave, 350 also seems plenty slow on the rotor. On our 80 we run about 2 to 2.5 on the concave and 450 rotor(specialty rotor). Every other concave wire pulled, bottom sieve wide open. Puts a little cob in the tank but not bad. 8 row head, 190 bu corn, 3.0 mph. Your 66 should have a little more HP than our old 1480. Split cobs is generally a symptom of concave set too tight. Chads