Over the last few flights I noticed the #1 exhaust valve might be sticking. When the engine was warming up, it ran rough under 1,000 RPM and the CHT and EGT were low on #1 (CHT was 150 where others were 200+, EGT was 700 where others were in the 900's). As soon as I increased the throttle past 1,000 RPM, CHT and EGT increased to their normal places.
The timing of this was fantastic, as I was just starting the conditional inspection.
Yup, definitely a stuck #1 exhaust valve. If you're wondering about the bracket I have installed on the cylinder, it's what I used to pivot my home-made valve compressor on (see http://www.vansairforce.com/communit...2&postcount=59
1/2 way through reaming out the guide, I took a pic with my borescope of what the inside of a guide looks like that's gunked up.
And after! Like night and day.
The only thing I changed from my original write-up (besides my new and improved valve compressor) was my method of keeping the exhaust valve seating for installation. Originally I used the "Rope Trick". One thing pointed out to me was there is a small chance of the rope forming a knot inside the jug, and then you have to yank it to get it out. So this time I tried using compressed air, delivered through the differential compression tester. I rotated the prop until the #1 piston was at the bottom of its stroke and the intake valve was closed. 60 psi of pressure seemed to be the right amount to keep the exhaust valve forced tight enough against the seat to install the springs.
All back together and ready for the next adventure! The whole process took me a little over an hour, including dropping and reinstalling the exhaust.