[vector1]

i would guess you are talking solid tappet, you can put a micrometer on the pushrod or lobe or rocker and watch the needle from base circle to where it starts to climb the lobe at an accelerated rate. there will be a gradual increase at first, at the middle of this or closer to the base circle is where i would set the lash at zero on a hot engine, cold could be something else but probably close. probably not real critical on a low rpm mild camshaft, and listen for any odd "noises". or on a warm engine i might set it at something like .010 and let it go, works on b&s lawnmower engines.