[Bill G]

Many things contribute to engine vibration. I recently found that something as simple as reassembling an engine with the flywheel 180 degrees made quite a difference. Another issue could be a crank that is out of alignment by more than a few thousandths of an inch. It doesn't take much. Some Model A's I've driven feel like they are going to shake apart over 45mph. Mine has its share of vibes too. One way to get a feel for it is to go for a ride with others who have Model A's or see if they will let you drive theirs. I find that I feel the vibes more in the steering wheel than being a passenger. Most Model A's that have not had many $$ on engine refinements vibrate, and all vibrate more than any modern car.

A very common thing is that vibration is generally related to RPM. I find my car has more vibration at 45 and over. I get used to it.

Also common is to have less vibration when the engine is under load either going up a hill or accelerating. More vibration when going down hill against engine compression.