So, you have trained mechanics telling you that it's your valves, and you don't listen to them? Get it through your thick skull!!! IT'S YOUR VALVES!!!!

Why are you supposed to do a valve adjustment on a completely cold engine? So, you have very little noise at start up, and so once it does warm up, the gap is even smaller. After sitting overnight, much of the oil drops out of the ehad, and it needs to relubricate itself. If you want to prove me wrong, before starting your car in the morning, drain a quart of oil, and put a fresh quart into the fill hole. If the noise is any more quiet than normal, I'm right.