So here is the last video on my series of measuring piston to valve clearance. this is using the loaded clay method. This is utilizing the actual assembled valve train, and clay. I have videos on measuring PV clearance, with the dial indicator method, using checking springs and clay. I think you may be surprised on the results. This may be one of the factors, why some engines with similar build specs, and cams, may make more power. Just another tool for you to utilize, you may be able to run that cam on the shelf, check it out. PS, 409 Cleveland done, and ready for the dyno.......stay tuned.