how can you tell wich housing is the front or the rear. or does it not even matter. i know wich rotor is wich but the housings look axactly the same. i recieved this engine dissasembled. so i am not at fault for not marking wich is wich.
please help. i wanna get my 7 running soon. btw its an 85 12a

 

on an 81-85 12A the rotor housings are the same front and rear

 

normally there is a stamp on top of the housing for F and for R,, the main reason is that during assembly minor ACV and EGR ports will line up internally on assembly
some housing with external port down by the exhaust port also require orientation during assembly

similarly s4/s5 turbo engines have only one coolant crossover to the inlet manifold ( rear rotor )

so you can see why there is need to differentiate between F and R on some engines if wanting to retain use of these passages

similarly again,, on FD engines ,, there is a blue /green or a pink dot above the sparkplugs for quick visual ID for which housing is where

granted,, some engines do not care which housing is where,, and also same for some rebuilds where there is deliberately no need fro ACV, EGR or coolant crossover routing

 

so in my case there is no matter wich is wich. there are no markings both are exactly identical. thank you guys for the help. much appreciated
off to order my atkins rotary rotor kit for the rebuild. (oem apex seals)