Recently purchased a used judson 40 hp. I found that the vane slots are slightly widened at the oped end. Is there a spec for wear limit here? Also, can the slots be cut to an oversize and thicker replacement vanes installed? Is anyone doing this?
No there is no hard fast rule that will tell you what is acceptable. Worn slots will mean you won't get as much boost and your Judson will be noisier.
The slots can be recut and oversized vanes fitted if the wear isn't too great. George Folchi is the expert in this (email@example.com) and can carry out the work.
The other alternative is to buy a new rotor and vanes. You'll find new rotors available from Ricardo on our "Buy & sell" page.