Allis Chalmers B with IH Magneto?

I recently purchased an Allis B which seemed to be running extremely lean (sounded like it was under heavy load even at idle) due to a bad exhaust manifold. I replaced the manifold and gasket and it's better, but still sounds like it's working hard just to run. I think the carburetor is fine as it's been gone through. I'm thinking the problem is timing. The original magneto was replaced with a rebuilt IH (appears to be an H4 type, but I'm away from the farm right now so I can't post a picture). The engine runs "best" when the mag is rotated all the way "in" toward the engine. It would be really great if I could rotate it even further, but of course I can't. It only strains harder the farther out it's rotated. So here are my questions:

1. Is this mag even compatible with the Allis Chalmers B? I can't seem to find it anywhere when compatible mags are listed. When it's running, it runs very smoothly, doesn't miss or anything, just sounds and blows exhaust like it's really working (especially compared to my other B). Exhaust is clean, no smoke whatsoever.

2. Is it possible or likely that the gear mesh is not sync'ed up correctly internally? Since I'm out of adjustment and turning the mag "in" only helps, can I just adjust the gears one tooth?

Thanks in advance!

Sounds like your timing is one or maybe two gear teeth late o the timing.

If you can find the TDC or CENTER line on the flywheel as well as the FIRE line you can check timing with a light off #1 spark plug. Without the light you can hand crank slowly and the instant you get spark you should see the TDC in the center of the inspection hole on the carburetor side of the bell housing. The FIRE line is 30? advanced from TDC and would be seen only when running at high idle with a timing light.

If the IH magneto does not have a running 30? advance it will never run correctly. I have noticed several Allis B's and C's with IH magnetos but never worked on one. To some if it is running it is better than not running and are not concerned if it is at its best. The IH advance is something I need to look up. Probly someone on the Farmall board would know if your magneto has the 30? advance.

I have had FM magnetos that the running advance stopped working and when it was in time on TDC for start you could not see the Fire line when running. When adjusted to where the Fire line was seen running the TDC could not be seen for start. The first one I had like that drove me nuts until I swapped magnetos.