Hi Folks,
I screwed in a new set of Unison plugs the other day. High time IO-360, so I thought I should be able to burn-off the remaining couple hundred hours of TBO with them. First issue, one of the plugs was totaly dead (nice to have an analyzer to zero in on bad cylinder!). No prob. New plug, away we go. I changed the oil over to 15w50, buttoned it up and filed a plan for a local trip. On run-up, one of the plugs in #3 appeared dead. I leaned it out @ 1800 or so and it cleared up. Great. Im thinking it got fouled when I was warmimg engine for oil change. Now im climbing out through 3000', and I notice #3 egt is rising. Switch over to left mag, sure enough, its now a IO-270. I decided to fly around the strip and see if more aggressive leaning clears the plug. The next fifteen minuted, EGT would go up and down every few minutes. Each time it rose, I confirmed bad plug. When it came down, mag check showed good plug. Then it decided to stay on-line, and the rest of the flight went as normal. Wierd hey? I guess I'll fly with it again to see if it is finally clear, but something seems strange to this low-time driver.
Ryan