[chrisk1500]

Cracks between the valves are *normal*. This is not to say that the cracks are a good thing. Normally they won't cause any problems but they have been known to crack all the way into the water jacket in the head.

Your best bet is to get the heads sleeved. A shop will drive a brass sleeve into the water jacket so that if the cracks go any further, they won't leak.

The cracks you really need to worry about are the ones that start at a valve seat and run up towards the precup.

To fix the problem you can either install new gaskets and the old heads, have the heads tested and plugged and then install them, or buy new heads and install them.