I've only ever had good luck running the valves if I primed the engine first. The lifters have a spring & hydraulic supported piston in them that you actually have to squish a little to prevent them from running with clearance (tapping). All past attempts to run valves on a 'cool' engine without priming it ended as soon as I started it up and listened to slightly more rocker noise than before I started. Since you have to pull the upper to get to them, I'd just prime them and do it once. Good luck!