A guy brought this into our welding shop and said the guys at the local machine shop referred him to us. We have experience doing they're aluminum heads for them but have never repaired a rotary. As you can see in the pics the damage is very close to the groove for the coolant seals and looks very tricky to repair without rendering the seal useless. Any help will be greatly appreciated.

 

the seal channel isn't magical, if you get any welding runoff/spatter into the channel it can be cleaned up by grinding the channel smooth again.

the crappy part is it appears he had the irons lapped already, doing the repair should have been done first so that the lapping process could have been done to level out the welding repair. some people aren't very bright though.

what i normally do is cut into the cancerous section to get to clean metal, do the welding repair, run a mill through the channel to clear it out then cut down the main surface.

the main thing to consider with rotaries is, try to avoid cutting in the center double oval area of the iron, that is like part of a bore of a piston engine.