Difference in 12A rotor housings?
 

I've never torn apart a rotary, guess I'll be starting soon. I see that the 12A has 2 different rotor housings: 81-82 and 83-85. Can these be interchanged, and if modifications are required what are they? I have an '82, an '83, and an '84 motor to cannibalize. So far, looks like I have two bad rear rotors (apex seal failure). I should be able to come up with enough good parts to build one motor, if the housings will interchange.

TIA.

the spark plug holes can be diffrent

Ah. I do recall the 'eyebrows' over the plug holes. Any other differences in water passages, etc?

the 83-85 rotor housings are a little stonger, they did it to help with chatter. if you do a search theres an 84 new model training book, where this is explained.

the housings are interchangeable.

the pre 81 housings are the ones that are slightly different