We have an 82 RX7 and it still has the wiring harness and ecu in it from the original 12a that was in there.

I am wanting to know if we found a 79 with a 12a would it bolt up just the same and use the same harness and ecu?

(I know we could do a 13bt swap or something of the sort but just wanting to get the car going at this point to take up less shop space).

Thanks,
Mike

 

A 12A is pretty much a 12A.
You should be able to strip the 79 down to the bare block and put it all back together with the 82's manifolds,distributor and smog gear/wiring.
The worst you might have to worry about is possibley some port matching or gasket cutting (if your even worried about that)

You could also put the 82's flywheel on the 79 engine for a little more zing.The 82 has a 6lb lighter flywheel than the 79,although the rotors are the same weight,so it wont screw up the balance of the engine. Just be sure the engines are actually the year you think they are.You can go here to determine all that,if your not sure.....

http://www.mazdatrix.com/faq.htm