thanks for the advice bob. i plan on checking it with a broomstick soon as i get my son to school. last night a friend stopped by and i let him listen to the knock. he said it sounds like i have a lifter going "flat"..... i have never had any problems with a lifter so i can't say if it sounds like one or not. has anyone had a problem with a flat lifter and if so does it cause a knocking sound? the knocking doesn't start at all until the motor warms up to roughly 175` and you can't hear it at all at idle. have to rev it up to 2500 or 3k before ya can hear it. i know i definatly have some lifters clicking but i just havn't adjusted the rockers yet (hate to spend the time doing that if i'm just gonna have to yank the motor again....). so what do you guys think?