Just an FYI, the *tick* is not a bad thing. Generally speaking valves do not loosen up. In fact, they tighten up on their own (again, generally speaking). Once they start to get tight the *ticking* goes away. Because they are getting tighter, this puts undue load, friction, and stress on the rest of the components. This in turn, robs you of horsepower and in general causes more wear and tear. If you can hear the *tick*, you're probably better of than when you can't hear the *tick*.