Rotating the crank and rods without the cam being in time and rotating in sequence with them can cause interference and damage to the cam itself. Many engines have notches for rod clearance made into the body of the cam for such clearance issues to prevent this(292 for instance, and the small Ford 6 engine), and those that don't still can hit the cam if its rotated so restoring the cam timing may be a first step before rotating the crank unnecessarily to prevent possible contact and damage to the cam just in case.
