The way Jason suggests is good. "cold" means room temperature. "hot"means running the engine for at least 20 minutes at a fast idle. I can tell you from experience that checking the tappet clearance on a hot running engine is a bit on the messy side and a bit of a nerve racking tedious job. If you do a good job with the cold setting, turning the engine over several times and re-checking to make sure the tappets are still good, then you don't really need to do the hot check also... unless you just want the experience.