John, thanks for the reply. I did hear a clicking, but it was faint enough that I thought it might be a dirty lifter. It had been making the faint clicking for maybe fifty miles before it became more pronounced, and I pulled the cover. You mentioned adjusters to tall, and that was my first thought. I measured them and from the flat on the rocker arm to the top of the adjuster screw, measures 3/4 inch. That seems excessive to me as the jamb nut is only what, 1/8 or 3/16. Do you know if anyone makes shorter adjustment screws? No I haven't pulled the opposite cover, but the only noise I heard was from the driver side. I thought of taller covers but I don't know if anybody makes taller ones. I saw some that had extra clearance but they were talking about spring keeper clearance. Larry