Hopefully the valves were fully closed when you adjusted them. (engine at top dead center on the compression stroke for the cylinder you were adjusting) If you were to try and adjust them at TDC on the exhaust stroke both valves could be slightly open (overlap condition) and if the adjusters were turned enough to provide the proper clearance in actuallity they would be very loose. I am not suggesting that you do not know what you are doing but this can easily happen to someone who has never adjusted valve clearance before. Was it making the noise before you adjusted the valves?