You might need to readjust your valves. You might have one or two valves out of adjustment. A few months ago I had some serious rocker noise coming from my stud mounted rockers. So I readjusted the valves and found a couple loose...on top of that one pushrod was clogged with a piece of gasket or RTV silicone or something so the oil wasn't going up the pushrod to the rocker at all!
So I replaced the pushrod, readjusted all the valves and everything is peachy.
