Mazdat

Hello,

I'm new to all this and just wanted to first say thanks for all the helpful info. I've read so far. I've always been impressed with the power output to engine size of the rotary, so I bought a car with a non runing engine to play with ('72 Datsun 510 with a 12A of unknown vintage). The previous owner had the Holley carb rejected and the shop did not set the oil metering system so it only started opened at 3/4 throttle, "It gradually lost power and died. couldn't get it restarted.", hence a compression of 70, 70, 70 psi on both front and rear (I was able to start the engine to warm it up for the compression measurements thanks to your ATF trick and how to take compression readings).


I'm try and track down the builder of the car, but if I cannot I have to turn to you for live help because I have looked at the archives to try to find more answers but haven't had much luck.

First is there a serial number or something on the block to identify the year of manufacture and if not then my second question is.....

I would like to know if rotors from an early 12A will work in later housings and visa versa ? I've noticed that the engines are grouped as '79-'80, '81-82, '83-85.

Thank you,

Mazdat

trochoid

iTrader: (6)

Welcome to the forum. Interesting question. Jeff20B would be the best one to answer your question. I might be able to muddle through it, then Jeff would correct me. To answer all of the differeces, it could be a long one.

If you haven't found the online FSMs yet, there is a link in my sig line.
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Rx-7Doctor

iTrader: (13)

I have never seen serial numbers on any parts of our engines.
I believe the tops of the housings are distinguishable by either having the raised H pattern molded into them or not.
As far as rotors. They are interchangeable.
They are categorized by weight. As long as you are using the correct front weight and appropriate flywheel with the appropriate year you are fine.
As far as the engines go the 79-80 years had the thermal reactor and the housings were different for this.
The 80 Ca models had a different middle plate for the EGR provision.
I hope this info is accurate.
If not I will hear about it.

Jeff20B

iTrader: (13)

I need pictures! My friend is going to do a rotary 510 soon. That's why I need pictures.

Anyway if you could post some pictures I could narrow it down for you considerably.

By the way, oil is better than ATF for getting a low compression rotary to fire. The ATF garbage gums up your spark plugs, cats (if you have them) and the experts of the ATF trick recommend changing your oil after the deed is done. All unnecessary if you use regular good old (new lol) motor oil. Next time, use oil.

Mazdat

Trochoid, rxdoctor, and Jeff20B,

Thank you for your help. I was trying to save the effort of tearing down the engine if I couldn't get new housings but if I understand correctly I should be alright as the rotor housings are interchangable exept for smog related items.

The engine has been "hot rodded" with all aftermarket stuff. I think I've found the right clue, the Racing Beat aluminum flywheel for '82 and earlier models. Unless he added it just to run a 215mm clutch for lower rotational mass on a later engine?

Jeff20B, The Mazda Datsun is a super simple swap. I'll send you some photos of the engine bay, motor mounts, transmounts (if I can squeeze my arm under the car) and take any measurements you may need.

Mazdat

trochoid

iTrader: (6)

As far as the housings themselves, there are very few differences and will generally interchange though the years. Biggest differences will be found in the irons and rotors. Once you know what you have, you can pretty much build an engine with any combo of parts as long as the rotating assembly is balanced and emmision ports are blocked off.