Block cracking is caused by people not cleaning out the holes that the studs go into, they contain old congealed oil, always clean these out and run a tap down them.
When I did mine I measured the depth of the holes, which were at least 4mm longer than the studs themselves, I just screw in finger tight, then a tweak with a grip on the stem of the stud, they have a shoulder at the bottom anyway to prevent them from going too far in, personally I don't beleive any block is cracked by the application of studs, more likely head trying to lift from too much pressure.
tabetha