Valve Free Drop

I just got off the phone from my piston builder and he asked me to provide him with my valve "free drop" in order to get my valve pocket depth correct. If I follow this correctly is this just how much the valve drops from its seat to the deck surface. If so, can I just set the head on a flat surface and measure a bare valve from its seat,(how much stem is sticking out of the guide) let it drop untill it touches the surface table and measure the stem again. (hope that made sense.

Is this correct or am I missing something?

Corey

 

That's exactly how it's done.