Joe- the reason for setting them hot is to account for expansion of the parts as they get hot. Steel expands at a rate of .000006in/in/degree if I remember right. So a 12" long pushrod would grow approx. .009 when heated from room temperature to 200 degrees. The block, head, valves, and everything else are also moving around as they heat up. For that reason, you are better off setting the valves a few thou. loose when cold and heating the engine up to operating temp. and then resetting the valves hot. I just did a rering and valve job on a nice '48 Chev. sedan delivery last week, and set the valves a few times hot before I was happy with them. I didn't do them running hot, I hate the little hot oil burns on my arms!
