360 motors

ok guys need help we have 3 engines that have spin #3 rod bearings 2 were rebuit with stock parts in drag car and truck and the 3rd was all brand new except the block and crank new rods,pistons cam and all 3 have spun #3 rod bearing has anyone else had this problem and can anyone help us we only turn all motors 6000 rpms clearance on rods were .002 and could turn motor over with 1 finger and any help would be appreciated