Heavy noise in engine

When I was on the way home I heard a light sound in the engine valves. I inspected the oil was almost empty, I filled it with oil 20-50 castrol oil and 10-30 oil i do not know the brand. Then I heard a heavy sound of the valves. when I pressed the gas pedal suddenly, there is no torque on engine and high sound if i pressed the pedal slowly there is no sound. i checked the valve clearance and distributor it is doing well but there is no ignition in three and four cylinder. When i pull the wire of spark plug on cylinder number four the engine still running and the three same thing . the engine is z24