Its common practice .
Everyone assumes the valves will expand tightening the clearance even more .
Without considering the aluminum block will expand even more due too the metallurgy involved .
Wondering ; the valve head is subjected to much higher temp then the valve stem .
Is it possible they expand at different rates .
The intake charge surely has some cooling effect .
Just go to the race track and make valve clearance adjustments and do your testing...................i think you'll find 0 works pretty darn good. There certainly are other things that are way more important than valve lift a few .001 this way or that way!
I had a problem a few months ago when i set the valves at zero after putting in a new head gasket. Ran great the first practice session. Next time out, it was down on power. Checked the valve lash again on the engine with the new head gasket the next day and realized the valves were not completely closing. Guess the head gasket compressed enough to affect the valve lash. Reset valve lash and is still perfect after multiple practices as well as running the CKNA grand nationals up front.
Lesson learned: reset valve lash on engine with new head gasket after a heat cycle or two. First and only time this ever happened. Was setting the initial valve lash slightly higher in the past after head gasket replacement.