if you have good set of rods you can get to them rpms 7800 that is hi. 8500 is to hi .003 is good for the clearance but what rods are you useing? and bearings ? the big end of the rod will want to move and this may be some of the problem the bearings will grab the crank and at this rpm the oil may have to much air in the the oil .so you need a good pan the a aero-wing conterweigt crank this will cut down on windage .and the mass will have to be very light why do you think you need to run it this hi??to go this hi you you need the very best rods steel billets or titanimum or a set of alloyed rods very good pistons and a light crank at 8500 rpm s a crank that is 80 pounds this hard on the bottom of the block with good parts 7500 rpms is much better the lower the rpm the longer it will live and you valve spings will last a lot longer