Banger Distributor Quit Turning?!

Got a prewar rod with an A motor in it. We had it running in the spring and now it won't run. Turns out the distributor isn't spinning. The motor was running fine in the spring and was shut off, it didn't quit. I have pulled the distributor out, turned the motor over the drive shaft isn't spinning either but it seemed to be engaged. Any one have something similiar happen to them or any suggestions. Is there a shear pin or anything? If I could even find an exploded view that would be helpful.
Thanks,
Craig

 

It sounds like the fiber timing gear broke. It's pretty common. The teeth shear off and the cam no longer turns. The good part is that it's not too difficult to replace and it didn't do any other damage when it broke like some modern OHV engines. Any Model A supply house will have the gear. I got the aluminum replacement when my flathead V8 fiber gear gave out at 60 MPH on the interstate.

 

Multiple possibles...to check cam gear, see if valves are moving. Some (I think Repro) distributor drives, the vertical gear driving oil pump and distributor, do have a pin securing the gear to shaft, and of course that can fail. I have seen one of those also with the screwdriver-like drive tab broken off. The gear drive itself is sometimes badly worn on the cam, but I don't think that would likely just stop, you'd probably have skipping attempts to turn.

 

If the dristributor spring(in the valve cover) is weak it will let it jump up and not turn. most likley the fibre gear. I had to replace one after it sat. When you say "driveshaft isn't spinning) are you talking about to the rear end?

 

The motor has compression, so the fiber gear appears to be fine. I checked for compression on the back cylinders too. I thought maybe the cam had broken in half. When I was refering to the drive shaft, I was refering to the distributor drive shaft.

Looks like I will start with pulling the side cover off and see what is in there. Not an expert on these motors... time to roll up the sleeves

 

Had a similar problem this year. There was so much gunk in the dist. shaft hole that it worked its way up and away from the cam and the spring couldn't hold it down in place. Was an easy fix.