VH4D wisconsin with Fairbanks Morse XV4B7 Mag

I have a vh4d wisconsin engine with a Fairbanks Morse xv4b7 Mag. At one time this machine ran. I recently had the Magneto rebuilt. The guy said that this mag wasn't the correct one for this engine. Now I can't get the engine to run at all. How could this engine run at all on this mag? Is this the correct mag? Thanks for anyones response.

Are you sure it ran well with that mag and is a VH4D not a odd fire VE,VF, or VP 4 and some VG4 ? The FM XV4 and ZV4 mags fit those older odd fire engines. A VH4D and later VG would be a later even fire using a FM-X4B7A or FM-J4B7A or Wico XH-2207.
Wisconsin catalogs

Well, it did run. Maybe not as well as it should of. The manual that I have says that the x4b7a is the correct mag. I just wanted a second opinion from some one more knowledgable than myself. It just surprises me that it would run at all.

My Wisconsin master parts book says VH4D uses
Fairbanks-Morse FMX-4B7A or Wico XHG-4

Yes it would have probably ran it missing and out of time but could never get timed right the dist rotor is running a different speed throwing timing off. You can download the magneto manuals for those used on Wisconsin engines at their site by looking under parts catalog section, then click Wisconsin and Accessories section has download manuals cover the mags, carbs and other parts. They may not have the VH4D parts book listed but I needed one two years ago and the guy at Wisconsin Motors emailed me a copy no charge just ask them. The FM ZV, XV & JV 4 and Wico XH-1343 mags used on the Wisconsin odd fire V4s are completely different mags with 4 pole magnet rotors inside, different impulse, different dist caps and dist rotor drives direct off the main shaft. Those odd fire mags had to be special made just for Wisconsin won't fire right on anything else yet they might fit because still had the SAE flange. The other mags used on even fire V4s are just regular 4 cylinder, CW drive mags with 2 pole magnet rotor and gear reduction dist gear the dist rotor runs on. Only thing special about the even fire mags would be the longer shaft for the gear drive and the gear otherwise they are standard SAE flange type. I suppose Wisconsin changed over so the mags wouldn't have to be special made for their purpose.
Wisconsin parts