In the short run I'd say no, but it will eventually lead to more wear... it's a vicious circle that won't end until you find out what's at the heart of it. If the loose clearance goes on long enough (if you can tolerate the high-pitched ticking at higher revs while riding!), it will eventually mushroom the ends of the valves where the tappets push them from hammering away as it runs. the earlier the better for less overall wear and tear. I've never had the top end of a 360 apart, but there are plenty of guys here who have and I believe the cam and rocker arms can be done in the frame so the job isn't nearly as big as it would be on a 350