I am buying a 1979 Mazda RX7 body and has no engine or transmission trying to find out if I canput a engines from a 1985 RX7 12a into the 79

 

Yes no problem at all using the 85 engine in the 79. Only differences really that I can remember are the oil coolers are different, but you can use the better 79 oil cooler on the 85 engine.

 

Thank you I am a rookie first car I have rebuilt and tired of some garages charging more than what it's suppose to charge all help greatly appreciated

 

Hey, Bubba - welcome aboard. I think you'll find that this is a very helpful group of guys who've been into the rotary life enough to know that helping someone to get their car sorted out is one of the simple pleasures. Seeing progress on someone else's car is sometimes more rewarding than working on my own.

As the other guy said, your "SA" (79-80 model year) car used a more efficient front mount oil cooler (abbreviated to FMOC), which can and should be used with whatever engine you decide to put in it. In fact, 1981-85 "FB" 12a cars used a less-efficient Beehive cooler mounted at the rear of the engine and which also mounts the oil filter. These aren't able to carry as much heat away from the engine, and your FMOC in the 79 is desireable. You will need to get the longer oil cooler flexible hoses, however. These can be found at Racing Beat or from a local hose supplier. Don't go cheap, as reliability of the oil cooler and it's lines is vitally important to keeping your engine cool and running well.

These cars tend to be pretty easy to work on compared to most, and their simplicity is something to be enjoyed. Dig into it, and post back here if we can help you with anything else as you get started,

 

Where it gets tricky is trying to use an 81-85 transmission. You'll want to stick with a 79-80 5spd trans as the later transmissions are longer and will not fit in the car without cutting the floor and modifying the dash. Any 12A will bolt right up to the early SA trans and by using the proper SA trans, you'll save yourself a TON of work and fitment will be perfect.

 

Thank you Long Duck I really do appreciate any help I have never got to get this far into working on a vehicle looking forward to this will post pictures as I go and will be picking you guys brains as I go

 

Where does the thermal reactor fit with the FB’s? Can you fit a 81/85 12a on the stock ‘79 exhaust without issues? I thought the rotor housings were different between these years .

 

The 1979/1980 engine side of the exhaust has a couple of ports that aren't on the newer 12A years. Not sure it matters much.



The other big difference is the square port on the engine side of the intake. The 12As after 1980 intake cover this port up. The 1979/1980 intake does not. I've tried to research this because I'm putting the intake back on my 1979 and noticed it does not cover this port.

The 1979/1980 does not use a computer to control the nasty emissions, so use a 1979/1980 carb and intake if you can get one.

 

If I am understanding the intake manifolds, the best option would be to use the FB engine with the FB intake manifold with an SA carb.