Well mine opened up .020 72 F to 185 F running. set it .005 intake and .008 exhaust and after hot had valve cover ready to pull quick. got back to 185 and it was .025 intake and .028 exhaust i can live with that.
It is amazing how much things grow. And since your cam was designed with a fairly tight lash (0.018/0.022), you don't have much room to tighten it up before you hit zero lash when cold.
I didn't see that much on my low deck KB block and 440-1 heads, but getting the oil hot as well as the water and then doing the check quickly can make a difference.
