Haven't commented on your problem,,just looking at the responses from time to time. Never actually had this problem or heard the noise in a 'running' engine,,but,,did have a friend have me come listen to an engine, on the assembly stand, no heads on it, and it made a squeeking sound once in awhile while being turned over by hand. I diagnosed it as a broken ring upon assembly. Turned out to be correct. Maybe when you are pulling plug wires and taking the pressure off that cylinder,,it is allowing the noise of a ring scrapeing the cylinder wall to go away..?? Maybe a leak-down test would show something
?? Just a thought...GOOD LUCK with your problem.
