Just the luck of the draw here, some people go through 3-4 sets of heads before they find ones without cracks.

But the thing is, I bet more than half of the 3800 heads out there on just normal everyday cars have cracked heads.

The cracks show up between the intake and exhaust valve, its a weak spot there, its such a small crack that you wouldnt even know its there and seems to never harm anything.