Joe is right, other things and especially exhaust leaks can sound like ticks. My engine, or valve covers to bes specific, sounds like it they have marbles in them. My neighbors 3.0 is extremely quiet in comparison. I guess some are louder than others.

What I meant about burning up the valves is that since the exaust valve looses its heat through contact with its seat in the cylinder head, as time goes by and the gap between the cam and valve gets smaller, the valve spends less time in contact. Eventually, it could over heat, or "burn up" the valve.

That said, I don't know when my valves were last done and I would like to get them adjusted in the next few months just for piece of mind.

Frank.