Alright! So I just picked up my 86 Non-turbo RX7. Came with a ton of extras, including clutch plates, suspension bits, the works. It also came with two (2) engines:

Engine One (in the car) has a bad rear apex seal. This is the original 86 engine.

Engine Two (In my garage) has a bad front apex seal. This is an extra engine from a 91.

My question here is, would I be able to use the front rotor off of the 86, and the rear rotor off of the 91 to rebuild ONE engine in to a running unit? I'm seeing that this is theoretically possible, but I'd like to input from folks who know more about rotaries than I do.

 

the simple answer is no. the engines have two different compression ratios and rotor weights. it simply wouldn't be a good idea.

my advice would be if you have enough space to disassemble both engines while keeping the parts completely separated, then pull them apart and inspect which is in better overall shape, then rebuild that one for use.