alright i still have a knocking tapping in my engine and was wondering about this. when we got the pistons put on the machine shop did not center the wrist pins. meaning if u were to center the wrist pins in the pistons the connecting rods were about 1/8 to 1/4 inch off center. so when the connecting rods were moved to be in the center one side of the wrist pin would be sticking out of the piston. i hope i explained this good enough to be understood. but ive been wondering about this since we put them in. the machine shop said it didnt matter. but i was wondering if this might be the knocking sound. what is piston slap anyways? and if it was a bad valve spring making the noise, would it run good because it runs great. also. on one of the connecting rods the main bearing was a little too long, but on the other side the bearing was a hair short so it compensated. being the impatient idiot i am i said to use it. could this also be the origin of the knocking sound? sorry for so many questions.