here’s an old Jam Handy film strip of a guy tuning up the valves on a running Stovebolt engine at the factory in the 30’s. Skip down to 3:25 minutes on the video to see that part.
Also around that part of the film it shows a guy with a prop who is listening to the engine for noises. Pop taught me that was the best way to adjust valves more than
Denny Graham Somewhere north of Sandwich, IL
Denny linked this YouTube video of factory setting valve lash