Is this “morning sickness”?

[Stewartb]

Go have a conversation with AK Aircraft Engines or Custom Aircraft Engines in Palmer. See what they say. They deal with Alaska-based engines every day and both are good at what they do.

 

[sourdough44]

I’ve had 2 bent pushrods over the course of ownership, factory new IO-390, I think close to 300 hours now. The most recent was last Summer. I think I treat my engine well, change oil, preheat when cold, never let it sit over 14 days or so. I have a modern engine monitor, keep everything reasonable.

I don’t have a date on my engine without looking. I can’t help but think the tolerances or materials are a little suspect. I’ve talked with my local shop extensively about it, looked on the web. Yes, the service bulletin comes up, cleaning the valve stems.

 

[MRC01]

I get all that, and I did operate lean of peak quite a bit for the first 400 hours or so on this engine. However my CHTs with anything deeper than about 20 lean of peak get below 300 pretty fast, and according to Mike Busch that causes valve guide deposits and sticky exhaust valves, which I did experience. Perhaps the sticky #2 was just inevitable. I was operating 40-50 LOP at 60-70% power pretty routinely before the valve sticking, and getting CHT in the 280-320 range. So maybe 10-20 lean of peak is where I need to be, but that’s almost just peak considering the fidelity of a vernier mixture control and atmospheric variations.

That's interesting, now your approach to run at peak EGT makes sense to me.

 

[Narwhal]

After cleaning/honing the #2 exhaust valve guide and lapping the valve/seat, I finally got a chance to test a cold start after the airplane sat for a week. Unfortunately it appears not to have changed anything. At least I can somewhat rule out a sticking valve, and if anything the valve seemed a little bit loose in the guide after the work. I’m not sure if too much wobble would cause this. I ordered the wobble test fixture to check it but it’s taking awhile to ship from spruce. Compression was 75/80. I put new spark plugs on prior to this start too. Only other thing I can think to try is maybe to change the ignition coils that power the #2 plugs, but seems unlikely that both coils would malfunction together. Would one plug/coil misfiring by itself be able to cause this? Maybe I’m just being too picky about the start smoothness because everything else is fine.