I have seen the same mushrooming with stock VW heads. I suspect that
people have trouble getting the valve adjustments right after a head
gasket job, regardless of the type of head. Many times here on this list
people have stated that they did not tighten the adjusters as much as
the Bentley states. This could result in more play than intended and
then the valve stems take a pounding from the adjusters.

Mark

-------- wrote:
> "this is just a marketing  ploy to add value"
>
>          DEFINATELY NOT  a marketing ploy.  I've had/have
> several AMC heads that the valves are mushroomed.  Can't
> remove them from the head without grinding the rocker end
> round again.  This was just cheap junk.
>
>
> Kenneth Wilford wrote:
>
>> I have sold many, many AMC heads with the valves that come with them
>> over the years.  I have also installed many of them for customers.
>> Maybe there was a problem several years ago with the valves, but I have
>> never had a problem with the stock valves that come with the heads.  If
>> the other suppliers were telling the full story they would tell you that
>> they are taking out valves that they say have quality issues only to put
>> back in valves that are not OE anyway (so who really knows how much
>> better quality of a valve that they are?).  ..............