Which 505 grind is it? 505T,505C or what I have ran those cams years ago, Isky usually suggested .032 to .028 on all those old grinds, even the same grind on a roller cam We ended up running them tighter by .004 to .010 with iron heads when set hot Post the grind # and I'll look in one of my old catalogs or call Isky and get the correct lash for you