I had confidence in the engine, as it has always run like a top. 240 hours TTSO, not a problem. Suddenly, out of no where, a stuck valve just as I landed. I was not even sure, until I was on the ground, and confirmed rough running and extreme low EGT on that cylinder. After parking, a pull through confirmed it. After seeking recommendations for a quick fix, just to get me back home, nothing worked. It was really stuck.
The hone arrived the next morning, and I went to work. I removed all the forward cowls and dropped the entire exhaust, so as to access the exhaust ports. I noted that the thin exhaust gasket on that cylinder had blown, and was mostly missing, allowing exhaust gasses to escape between the cylinder port face, and exhaust flange. No damage to either. I had had loose nuts there, which I had previously tightened. I though no more of this at the time, but I do now!
I used the rope trick, and released the keepers and springs. I had to pound on the valve stem to get the valve into the cylinder. With that, I honed, and used the "go-no go" gauge, to confirm the honing was done as required. Once done, with some finger and tool art, I got the valve back in the guide, and its motion was a thing of beauty. As the exhaust was all off anyway, I similarly checked the other three cylinders. Their valves were perfect, no honing required.
Four new blow proof gaskets, and new rocker gaskets, and the end of a long day heard the engine purr again. An hour long test flight to confirm success, and return the tools, perfect. So I continued my original trip, and caught up to the rest of the group.
I was puzzled by the seemingly unrelated coincidence of the blown exhaust gasket being the cylinder with the stuck valve. I discussed this with the group the first night, and a retired Continental Engines engineer explained it to me: If the exhaust gasses are not carried well away from the cylinder as intended, that cylinder will get locally hotter than intended. As the guide is running hotter, it expands more, and allows more gunk to accumulate. Finally when I pulled the power off, and made a low power approach, the cylinder cooled again, and that was it for the guide to valve stem clearance. It all makes perfect sense.
So the lesson is that to keep the engine running properly, and cool, assure that the exhaust gaskets are totally effective. With the 13 hours of easterly flying time to prove out the quality of my repair, I had the confidence to take it out for some air to air with a friend. The result is my new avatar
All those references are gone... along with any mention of model glue and fabric paint repair
At least I presume this is what you're referring to:
