Had a chance to speak with my mechanic this afternoon and got a little more information on the problems he was talking about specifically.

The fault he thinks he's seeing doesn't have to do with the head itself at all (my mistake). What he told me is that the effect he described (head changing texture slightly, etc.) has been happening to all the heads he's reworked, and that it is a side-effect of the heat that changes the aluminum and makes it more brittle/fragile than normal.

The problem he was telling me about involved the head gasket itself, and affects the 1992-1993 7xx/9xx models. Over the past 4 months or so he has done 7-10 head gaskets on these models, and he informed me that, at least for him, that is an unusually high number. Additionally, he noted that the gaskets on these models shouldn't be failing anyway, and that they should be lasting much longer than the 9-10 years their failure is indicating.

It's possible this is just a fluke, and that he has seen a wierd number of head gasket failures in his garage lately on these models for some other reason. However, it is also possible there was a run of bad gaskets employed or that the gaskets used in these later models weren't "up to snuff".

Hope this information helps.

regards,
rt