Originally Posted by
hsukaria
I suspect that it might have leaned out in flight. I had it running extra rich later because I could tell it was getting quite hot even though it worked well with that setting before. At first when it started acting up, the glowplug got scortched, looked like the coil got scrambled. I replaced it with a new plug and ran it rich(er). It would run normally for about 2-3 minutes at WOT and then suddenly quit, regardless of HSN setting. The idle and transition worked well. When hot, there was practically no compression. But when cold it has a good "pop" from compression. I checked the head bolts and were on tight.
Distraught in Detroit
Well, you were too lean for sure. No compression when hot is a bit scary, but if it comes back cold, it might be okay. Always richen the needle and re-tune each time you go out to fly on a different day. Never assume that a setting from one day will work on the next.
Tight head bolts are a good sign, it wasn't run way too hot...