What a difference a day makes! Back on the vibration source...the prop AND spinner were
both off. Has anyone had trouble with those Great Pains aluminum spinners that come with the ARF?
There are bubbles in the tank on this plane as well, with a balanced prop/spinner, it didn't change, so the tank is coming out next, not to hijack the thread, just thought I'd just say you told us so, and you're right. Air is getting in the tank from full the pick up fuel line (suspect) during the whole bench run. It was interesting the engine didn't seem to pulse or drop rpm (by ear).