looking at a N/A ported vehicle for sale and it appears to have a rx4 or rx5 (cosmo) housing at the back and a GSL-SE or FC rotor housing at the front. Car seems to run reasonably well, but am I in for a surprise down the line with the mismatched rotor housings, or should it be ok provided the rest of the build is up to scratch? Thanks

 

if exhaust ports are matched then the rx4/ gsl-se combo is Ok
( one housing will have an oil squirt you block )

if that is an FC housing then it should be belting out coolant somewhere as there is a total incompatibility in the water seal groove types that requires mods to fix
( namely the FC housing grooved to provide 2 water seal lands )
there is also a clash at high rpm and boost with early rotors in late housings that needs a light dress of the rotor face

so,, if its not belting water and the exhaust ports look like they have been matched up = aok

PS
FC and GSL-SE housings can be ID from each other in several ways.. GSL-SE tend to have the copyright blurb on top and the oil squirts closer to the inlet manifold
some FC housings have a higher leading plug than others.. beware

 

Thank you for your information. Appreciated.