A 25 LOP EGT will be 50 degrees higher than 75 ROP but changes the mixture
creates in the combustion timing offset this so that CHT is usually the same
or slightly lower. This small difference in EGT has no effect on the engine
or exhaust system whatever. Hard to say what was going on without at least
one cylinder of CHT data.

None of this should effect your oil tempearature. Ours runs the same in the
winter as the summer because the thermostat just sends more or less through
the oil cooler.

An important part of operating an engine without an all cylinder analyzer
this way is to keep power settings at or below 60%. You should make up a
table from your POH for reference but flying with carb heat on will make the
engines like the O-320 pretty much self limiting. It also improves the
mixture distribution so that the engine will run leaner with acceptable
smoothness. The drop off in RPM and onset of roughness is less abrupt and
more predictable with carb heat on.

I now use WOT for almost all cruise above 3000 feet.

You can read more he http://baldeagleflyingclub.org/Manual.htm

--

Roger Long



"Darrel Toepfer" wrote in message
. ..
Roger Long wrote:

Note how smooth the engine sounds with carb heat on when leaned to about
a
100 RPM drop. Throttle was full open and CHT were right where they are
shown
20 minutes later. This video was taken at 5500 feet.

I did this on a recent cross country flight, 100+ miles each leg. The
oil temps ran higher than normal, as well as EGT's. I wasn't running WOT
and was only at 3500' ASL. We don't have CHT instrumentation and what we
do have is analog...