I have the same set up, and had the same problem on a couple of valves when I first started the engine. What happened on mine was the rocker studs started to back out of the head, opening up the clearance. The directions state that the studs need to go into a CLEAN, DRY hole, use Loctite and propery torque them. I had a couple back out slightly, causing extra cleance. This might be the problem. Good luck.
Paul #3040
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