I have a 93 f150 with a 5.0. I kept hearing an annoying ticking so I checked my compression and found that number eight was not looking so good. After pulling the head I had noticed that the exhaust valve had a small piece along the edge broken off. I put new rebuilt heads on and the noise went away. NOW its back, and that number eight is burning plugs. would this problem reoccure and why? ofr maybe its something new

PLEASE HELP


As far a the spark plug goes the white insulator that houses the diode is melted and the diode gone, the plug has no impact damage and is dark but not charred, its almost like a plug would look if it was misfireing. I did change the plug but the noise is still there