Posted for "colyncase on earthlink" <colyncase@earthlink.net>:

 Jim said,
 If anyone wants my opinion it is that the exhaust valves on the TSIO-550E can
not cool themselves enough while LOP even when power is back to 28/2400
because it is still at 1550F EGT and that makes the exhaust valve so hot that
the valve seat has to be wide and perfect to take all the heat ouf of the
valve head, or the heat goes up the stem and burns the oil off the stem
therefore wearing the stem and guide very fast.
 
 Jim,   I'm not following your logic here.  Why couldn't you lower egt by
going leaner?
 What EGT are you getting ROP?
 Will a valve seat that isn't perfect run okay at that temp?    Seems like you
have to have great valves at any temp on this engine.
 
 Colyn