I just bought a 1980 Mazda RX-7 (really cheap), that had a bad engine (needs to be rebuilt). I came across another 12a engine for $250

Well, i went to the place to get it, and the guy says, yeah, same engine, it will work.

Now, looking at it, the engines are different. I believe the second engine i got is a different (newer) year, they are both 12a's, but the valves on the top of the engine (the vacuum control valve, releif solenoid valve, etc...) are different

now, my question is, will i be able to take all of these off of the engine that is presently in the car, and put them on the engine that i bought for $250

basically all i want to use off of the engine i bought for $250 is the main part of the engine (the block...) and use the control valves, and carb off of the engine that is still in the car.

 

Yes you can use it. They are the same.

Mike

 

The emissions systems between '80-earlier and '81-85 12As are TOTALLY different. The engines themselves are different, because the air passages from the air pump to the exhaust system are routed through the intake manifold and center housing on '81-85 engines, and through external pipes to a heat exchanger first before going to the thermal reactor ('80 and earlier).

In short, yes the engine itself will work fine (I have an '84-85 engine in my '80) but there is no way you're going to put the '80 emissions equipment on it. You're going to have to go non-emissions, or convert to '81-up spec (need a catalytic converter, wiring harness, emissions computer, other stuff?)

 

Actually, I don't mean to be nit picky but, the engine themselves are the same. The things you refered to as different are not the engine.
Since he said "basically all i want to use off of the engine i bought for $250 is the main part of the engine (the block...) " I didn't feel a need to mention these differences.
Although, any 12a from an rx-7 will bolt into any other 12a equiped car as long as you use the componants suited for the chasis, there are differences. The 83 down has a lighter flywheel assyembly while while the 84-5 use lighter "N" rotors (called N rotors because they have the letter N on the cumbustion face). The best set up is to use the later rotor assyembly with the early flywheel assymbly. This is a trick you learn real quick racing ITA where you have to use stock engine.
Just make sure you use the clutch and PP for the engine you have and not the chasis. You can tell by looking at the flywheel and if you need to know the difference, just ask.

Good luck,
Mike