12A's

[l-arsouille]

I start this topic to share my experiences with my different 12A's and also to learn more about them.

First the one I bought one year ago, it was a good occasion to know what was inside for real and to start working on rotary engine.



So I started the disassembly process and ended with an almost naked engine



After that I ordered the 54mm socket needed to unlock the flywheel nut, so when I was waiting for it, I started to clean some pieces

The well known by all the rotary engine enthusiast, Blue Box of God



The intake manifold (pretty happy with the result )



The oil pan (beurk!)



Air pump (why not, even if I don't put it back on, I was in a cleaning mood)



Don't have any pictures of the water pump cleaned

After I received my 54mm socket, I started the most exciting part



Almost there



Finally



But the rear was a bad surprise



Since that time, I'm still cleaning this rotor every month to make it looks better to have it as a decoration part. And I still have to take the measurement of all the other parts to see if I can fit them again (iron, apex seals, side seals, etc...)


Now back to present day, last week I get my hands on 2 12A's from Belgium, one was blocked and the other was turning by hand, so today I started to strip the blocked one (who is more dirty from the outside but I don't know for the inside)



The oil who came off the engine was not so dirty, but what stayed in the oil pan was !



And after a bit of work, I'm almost ready to open it




Now I have questions, how to know from which year is an engine ? I've seen the post with the flywheels shape and weight, but the flywheel from my first engine looks like a S2 but the last oil change is dated from 1981 with approx. 80800 miles... so probably an S1 with so much distance on it in this short amont of time ? Is there is another way to identify the exact year of an engine ?

[Steve-A]

Ouch That's some nasty looking oil and rustyness.

I believe s1 engines are meant to have the 'small port' center plates, where as yours both look like 'tall port' plates. This suggests s2. The fact that you have the square block on top of the housings, rater than an H shape block, along with the flywheel shapes, suggest they are s1 or s2.

[l-arsouille]

Hum, I had a look at the flywheel of the first engine, it has the "21" on it so it's should be a S2 engine, but on the intake manifold there is 4 ports and the two center ports are small, when they are "tall" on the center plate ?

And this is the same on the second engine, "tall ports" on the center plate and also on the gasket, but small ports on the manifold and the flywheel is a heavy looking one (like the S1) but have the number "31" on it, so S3... and it's lighter. So I can't find any informations who are saying the same thing.



But this didn't stopped me, I was writting the numbers on the tension bolts in order to untight them when something strange showed up !



Any bet on this ? In the manual from 1980 there is a bolt on n°6 :|

Ok, at this point, the horror show did start : Rear rotor, housing and plate



Front rotor and plate



I was very disappointed, I was hoping that at least one of the parts would be good... I still tried to clean the inside of the housing



Not too bad. But now there is some "scratch" on the side of the housing and some marks close to the spark plugs holes, do you think they are still usable ?



Well, next step is to try to clean the plates, and I put a rotor in a rust off bath, I'll see in 2-3 days

[ian65]

that's in a poor condition.... it looks like it's been stored at the bottom of a fish pond.

[spoddy]

well i am no housings expert but the last pic doesn't look too bad.
some of the chrome has come away at the edge, but i'd say there'd be enough for a decent compression
from this housing and it can be reused again.

the other parts look really bad, but it'be interesting to see how the rotors and the side plates will look
after a few days in your anti-rust bath you spoke of.

[ian65]

Tool is the man when it comes to engines and housings..... he'll be along to give his view on these housings.

[spoddy]

how much are 12a's worth and are they fairly handy to pick up now a days??
i'm just wondering as due to their rarity and people's preference to installing 13b's for more power etc.

[RamoNZ]

Engine 1: elec dizzy, tall ports and later alternator = S2
Engine 2: elec dizzy, tall ports and beehive oil cooler = S3

Factory tolerance for chrome flake is 2mm but with 12As you can be more lenient due to their scarcity. Don't look too bad from the pics though.

[TOOL]

Housings are S2 on that last one but beehive fitted. Frankenrotor.

S3 rotors have F and R stamped on them as well as N for NA. That'll tell you what rotating assembly you have. Housing and beehives get swapped around.

Your housings are ok, not great. Don't throw them away cos they're getting hard to find. Measure up and check the spark plug holes for cracks and corrosion in the water seal recess.

The housing on the first engine is junk. The others look ok. A little chrome peel on the exhaust stroke won't matter too much.

Where in France are you?

[l-arsouille]

spoddy, there is only one rotor in the "rost off" bath, not the plate.

I tried to clean the center plate today but after it went a bit better it appears that there is too much damage on the it :x So now I will use it has a part to test different cleaning method, see what is working and what is not.




Ramon, the tolerance of 2mm is per side, so 4mm total or 2mm total which mean 1mm per side ? I guess that's the last one but I have to ask.

Now I know a bit more how to identify from which series an engine is, thanks ! There is only a F and R stamp on the rotor of the first engine so you were right, and I saw a N on one of the rotor of the second engine, so you were right again ! Thanks guys ! I will come to you if I have another one to identify

Tool, I'm living in the south of France near Toulon.