ticking sound from the valve
 

hello everybody, i was wondering if anybody can give me any idea of what is the ticking sound coming from the valve. i bought the car used and when i bought it i think it already making that sound. i never pay attention to it because i thought it's just normal.it makes the ticking sound at idle then dissapear when i step on the gas. do you guys it's justneed a valve adjustment or oil sludge, etc? what do youguysthinkit's? advance thanks everybody!