.004" cold to .012" hot is my belief. Here is a plot of a 906 intake cam at the valve. The green line is .012" lift and the blue line is at .004". The factory designed the "clearance ramp" long enough to keep the valve seating velocity low, hot or cold.
There is a 56 degree change from cold to hot going from .004" to .012" on the 906 intake. My guess is the engine really wakes up when it gets hot.
