Jim,
If you were climbing with CHTs in the 400
then most of the damage was probably done in that configuration.
As to the following:
>>What I didn't pay much attention
to was EGT while LOP which was TOO HIGH at 1550F, in my humble opinion. 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.<<
Ah… that is the conventional
theory and wisdom - - that is - - that HOT EGTs translate
into HOT exhaust valves. It just turns out that isn’t
true. The value of the exhaust gas temperature flowing past the exhaust
valve is often inversely proportional to the temperature of the exhaust valve.
I ************* KNOW
*********** that comment appears to be completely crazy and verging on
the area of silly.
But there is good hard data on this
subject going back to the 1940s’ That data shows that
the exhaust valve temperatures follow the CHTs - - NOT the EGTs.
And by advancing timing, as just
one example as to why this is true, one will LOWER THE EGTS - - but
that will make the exhaust valves run very much hotter (along with the CHTs).
By retarding the timing a lot, the
EGTs go VERY HOT - - but the exhaust valves get very cool - - along with
the CHTs.
In short, EGTs do not correlate with
exhaust valve temperatures very well at all.
>> My second set of cylinders had
stem and guides wore beyond limits at 82 hrs and I hadn't gone LOP for the
first 40 hrs and then maybe half the time for the next 42 hrs. This is the
mechanical fuse, so to speak, of the Continental engine, the exhaust valves.
Now I run ROP and let the fuel save my exhaust valves and save money. I use
about 4 or 5 gal. more on a 540 nm flight and go faster and quicker.<<
I suspect your problem was the
dimensional fit of the exhaust valves/guides before you ever started your
engine the first time.
Regards, George