>>As a side bar, I don't run LOP anymore unless I need to stretch
the range. This after replacing all 6 cylinders at 215 hrs from new and then
the second set after only 82 hrs. Both times the exhaust valve stems and guides
were out of serviceable tolerance. This could be a very long thread but will
have to wait. <<
Jim, you have to stay focused on the
science of this. It is easy to let anecdotal information or isolated personal
experiences like yours overwhelm the decision making process.
Consider, I can show you an 87 hour
factory NEW TCM engine on a NEW airframe from about 18 months ago that has
exhaust valve stem/guides worn out. Engine was operated ROP for the whole
time.
TCM claims they
have revised that configuration and now post-ream
the valve guides - - and that should fix the problem.
So, what were your cylinders? TCM’s?
Somebody else’s ? Overhauls? What is the history?
So far as I know, there is absolutely no
evidence or even any well considered engineering/scientific hypothesis as to
why operating an engine at 75% power at 50 to 100dF ROP should be “better”
for the exhaust valve guides as compared to operating the same engine a the
same horsepower with the mixture set to 50 to 75dF LOP.
There is lots of evidence that poor
dimensional fits for valve guides and stems and seats causes the precise
problem you experienced.
Regards, George