[TerryH]

A couple of years ago my A was making a faint knocking type of noise that no one could isolate....using stethoscope or wood dowels. It ran fine, but got slightly worse over time. Then, one day, I decided to take it to our local Model A mechanic, but on the way, it suddenly quite running. Had it towed via AAA to his garage.....a couple of hours later we determined the fiber timing gear had stripped out, and replaced it with a new laminated one. Noise was gone; in this case it was a fiber timing gear going bad....yours sounds much worse, so may well be something else, but those gears need replacing in any event.