David said:

>What causes a valve seat to be pushed in? An answer to that  might provide
>insight into the question of GEX rebuild quality (and possibly an error on
>my part as well).

-Maybe- too little valve spring, either poor quality or worn springs, this
causes floating valves, this can happen even in the lower RPMs, especially
with the Bus' low gearing, certain 'high performance' cam/lifter/pushrod/
rocker combinations can make it even worse, floating valves can do all
sorts of things to seats, guides, retainers and pushrods... But 5 mm into
the head!? gee...

-Maybe- it's because of the head-crack repair
techniques they used, -maybe- they welded around the seat area and now this
area is too soft to support the seat properly...

0.02

Brian