Hi The Hood is open and the throttle is pulled to a higher idle to let it warm up. The Jeep vibrates, even at idle, and I was told by my mechanic after extensively probing him, that all jeeps vibrate slightly as they were not made to high tolerances like new cars today. The sound heard is the hood and latches vibrating against the windshield since they are open. Also, there is stuff in the glove compartment (wrench, extra spark plug, gap tool, etc, that vibrate from the engine) Thanks
these flathead fours have only three main crankshaft bearings and no balance shafts like modern fours. ..they vibrate more or less throughout the entire rpm range...that's normal.
