I shaved 1 mm off the spacer and reinstalled it. I flew for two hours and did multiple touch and goes and other fun things to wring out the engine at all RPMs. the carbs stayed put.
That spacer was 8 millimeter and I only had trouble with the left one. I didn't touch the right side. (no.2 aft looking forward.) I put on the nose cone tonight, I"m almost satisfied.