This follows a previous post in which I reported roughness at full power with my IO 360EXP. The roughness was always accompanied by a significant drop in EGT on the #3 cylinder. Acting on a Lycoming rep's advice I had the #3 cylinder exhaust valve guide reamed. I've now had 15 trouble free hours of operation. I plan to do the other cylinders on the upcoming condition inspection. I bought a Yankee Corp reamer through Amazon for $48 with tax & shipping.
