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BRS wrote:Bryan, you didn't mention so I won't assume. You did verify both the top and bottom plugs are firing ok - right? Only one plug firing will give a hot egt as fuel burns slower and gets out the exhaust before it's ready.

Brock,
Mag check has been good. Generally I switch to the primary ignition only by 1000' AGL or so.

How are the CHTs. Is the side with the higher EGT also showing increased CHTs? If not then It could be as simple as the placement of the EGY probe in the exhaust. Just a slightly different angle or distance than the others could certainly cause a 100f difference. CHTs are what you really need to monitor and worry about. When they get too high you start damaging the head and can loosen up the valve seats. EGTs are less about the absolute number displayed and more about the relative changes when leaning. If your CHTs are good I would keep on flying and just periodically pull a plug to make sure it looks good and maybe borescope the valves at each oil change.

The #1 CHT has been reading 100F. It seems faulty, 200-300 is more normal for me.

The troubling thing is the big change from normal after 200+ hours.

Bryan

If I remember correctly, didn't you change the needle in the AeroInjector? Richer? Or leaner? Did the high EGT start after that?

Bob,
Here is the sequence. First I did the annual and all that entails:
1) torque heads
2) adjust valves
3) change plugs
4) compression test

Then, some extra credit:
5) re-shim engine
6) redo main seal/polish flywheel surface
7) Fresh air induction

So I noticed the EGT being higher after fresh air induction. Makes sense, more air and the same fuel means leaner. So I adjusted my #2 needle a few times, then swapped to #2.5

It's entirely possible the high EGT on #1 was caused by something else and I attributed it to the fresh air induction. Maybe I have a bad or leaking spark plug on the #1 cylinder.

I'm halfway through my differential compression test. So far I have:
#1 80/72
#2 80/67

These are cold and I hear air in the crankcase, so it's getting past the rings. The numbers don't seem that bad.

Mike Busch has some thoughts on this.https://www.savvyaviation.com/unbelievable-compression/

Thanks Mike!

Final results:
#1 80/72
#2 80/67
#3 80/64
#4 80/74

The adapter was not threading happily into #3 and I suspect that lowered the reading a little.

Boroscope next.

The valves look good. I'm going to swap the spark plugs on the #1 cylinder. They are new at annual and maybe one is faulty, or leaking even.

It may be worth checking that you don’t have interference between valve adjusters and the rocker cover, due to an excessively compressed cork gasket.

RodgerC wrote:It may be worth checking that you don’t have interference between valve adjusters and the rocker cover, due to an excessively compressed cork gasket.

Thanks Rodger. I've got rubber gaskets and there are definitely no witness marks on the inside of my valve covers.