I don't have my Mazda manual with me (I'm away from
home)and I need to know if it is normal for the rotor
housing to have slight grooves worn into the outer
edges and depth limits. The two engines I tore down
at home had grooves and the one I just tore down  at
the junk yard had, not only the outer edge grooves,
but also some in the center surface of the chamber and
the owner is telling me the engine is rebuildable.
Is it????

It might need new rotor housings. Most are rebuidable if
you use new rotor housings. If you are really talking about
end housing those can be lapped.

Paul Lamar

Bruce's video talks about the allowable amount on the edge of the
rotor housing. He doesn't talk about an allowable center ?groove?
though. He also says Mazda specs don't allow the edge wear. He say not
much but new will meet Mazda spec.
--
Blake C. Lewis