The valve cover bolt on the intake side of the head lines up between the number one intake and exhaust valve. Probably into the wall between the two runners if I guess. However if the head was cracked there-(Into the exhaust or intake port) I don't see how that is going to change a simple compression reading? That area is a long way from the combustion area of the head where you make compression. Still a valve hanging open is my guess. An exhaust if it is not popping back into the carb. Good luck!
