At about what mileage do the rotor tip seal crak / split at?
 

Im looking at buying a Mk3 RX7 but people say the rotor seal go! and was wondering at roughly waht mileage this mite happen? and is it expensive to replace? and is there anyone in the UK which would be able to do engine rebuilds?

thanx

What you are refering to is the apex seals.
There is no general mileage range really. More than any other part possibly, they depend on very exact, proper, and punctual maintenence, so the reliability of your engine (and the apex seals) rests completly on the owners (and previous owners) shoulders.

So to answer your question... anywhere from 2,000-to-200,000 miles is an good estimate range ;)

is this a common thing with RX7?

they break, buty with general care, 200k is normal

Yeah, and you don't ever even need to adjust the valves or change a timing belt/chain etc whatever. :)

Besides, to rebuild a rotary engine is about as complicated as rebuilding a single cylinder lawnmower engine, or a Nikki (or Hitachi) carburetor.

Apex seals only break if you abuse your engine, basically. Detonation ! ! !