I have a sweet running '82 12A/automatic with only 92k on it. I just bought a whole '85 12A parts car for its 5 speed. The '85 only has 97k on it and it seems to run good but I don't know its history. Is there any advantage to swapping the engines when I install the 5 speed or are '82 and '85 12A's completely identical except for the oil cooler?

Also, is the better looking '85 dash w/ heater controls easy to swap into the '82?

Thanks
GA

 

Yeah, the '83-'85 rotors are the lightest stock 12A rotors Mazda ever made. I prefer them over the '82 and older rotors. You must also get the front and rear counterweights (or correct flywheel) if going with '83-'85 rotors. All the seals are the same.

You need to do lots of searches before taking on a project of this magnitude. Try to find out why you must use the correct flywheel for example. You know, small things like that which equal engine death if you screw up.

 

Thanks for the info Jeff20B. Sounds like I'll be best off to swap the whole engine/tranny assembly. Won't even have to separate them.

 

^^Sounds like a good idea but I'd keep your FMOC. Post pics of both cars

 

Yea,the later engines had their good and bad changes.

The lighter rotors arent as easy to swap as other items,unless you are building an engine. A light flywheel on an older style engine will make far more difference in rev response, than the couple lbs you save from the newer lightweight rotors.

The 83-85's had a radiator with more frontal area,but were strapped with the crappy beehive water/oil cooler.The 79-82 air/oil cooler is always a better choice and is easy to adapt to the 83-85 engines.

All the 79-85 12A engines had about the same internals and the same HP/torque output.There were only minor external changes made to the intake,exhaust and smog items,most of which dealt with reliability and emissions control.

 

I sure like those 84/85 12As, been driving them heavy now for six years and haven't had a problem with one yet. You need a carb to get the best effect though and a clutch is nice too.

Ray

 

I'd keep the '82 motor and just source a flywheel and counterweight. You know its history and it's been adequately cooled all its life. The '85 has neither of those advantages.

 

If you keep the 82 engine get the 82 flywheel, its the lightest of the stock flywheels ( like 23 lbs.) I swapped an 82 flywheel into my 80 SA which had the 30 lb. flywheel and I can feel it. Revs up and down quicker but its heavy enough to keep things smooth.

 

225mm Clutch Vs. 215mm Clutch.

 

Good point. The smaller clutches are getting harder to find. Even so, I'd stick with the engine you know and keep the unproven '85 in reserve.