I used to hear the air cleaner vibrate (metal to metal) when I start and shut the engine off. I replaced the 3 rubber mounts with new ones and it did the same thing! This post just made me realize that I do not have the air cleaner vibration anymore! The reason must be that my engine is running better than ever. It starts and shuts off instantly and is smooth without shakes. I still have the old damper bolt (not gold). I have slowly gotten the engine to run better and better with the following items done over a period of a year or so: Getting rid of air in the fuel system (no bubbles- even the smallest ones), adjusted internal IP base pressure to 25 pi with my adjustable fuel pressure relief valve, timely valve adjustments, and Italian tune ups.
