Help identifying 10A/12A engine parts, please
 

I've run across a cache of what appears to be pre-'79 10A and 12A engine components - some used, many NOS. Where can I find older parts catalogs to try to identify the vintage of this stuff?

Example part numbers:
1665-10-200D Front Housing
2050-99-105B Intermediate Housing
0877-10-300B Rear Housing
0820-23-050A (or -030A, not sure) Rotor Housing 10A
2090-23-113A Rear Rotor 12A
2090-23-103A Front Rotor 12A
2090-11-301 Apex Seals 12A
2329-11-301D Apex Seals 10A
2113-11-301 Apex Seals 10A
2090-99-100 RX2 Gasket Set (this one is sort of self-explanatory, I guess)
0820-23-180C Engine Oil Seal Set
(First # unidentifiable)520-11-111F Rotor Bearing 10A
2090-11-511A Eccentric Shaft & Counterweight

Thank you!

wow sweet! the next book i'm going to scan in is a 70-78 rotary part catalog, it lists all the housing part numbers and applications.

should be like next week, maybe monday

Can anyone determine the mfg year(s) of these 12A housings from the housing pic? I know that it's tough to see detail in my crappy pic.

What are distinguishing characteristics between 12A rotor housings through the 70's and early 80's? I've searched, but not come across anything definitive.

Same info needed for front, int, and rear housings, if anyone would care to take the time.

Lastly, is there a demand for 6mm 10A or 12A apex seals, related seals/springs, or related rotors? How about a complete 10A?

Thank you!

Well the Pre 1974 so 1970-1973 12A housings say 12A ontop of the licensing toyokogyo/NSU Stuff. Main way to tell is that they have a plack with a 1 like in the picture you posted, or the have the spot for it. all 10A housings should look like those 12A housings except narrower. Unless if you have some rare Japanese Cosmo housings from a L10A or L10B, the pre 74 12A housings and the 10A's will look very identical, only difference is the size and the number stamped on it. 1974-1978 (I think its 78) the housings Say Mazda with the cool old mid 70's font where they used to have the plack with the 1. Also in 74 the 13Bwas introduced.

Also Pre 1974 rotors have 6mm apex seals and 6 side seals per side. The rotors are also one for the front and one for the back, due to the cut for the compression, so you may run into 2 rotors that you put them side by side, both gears facing the same way and the cut for the compression wont match up, Here are pictures showing what I mean.

This stuff you have is pretty cool, very hard to find stuff. If you're going to sell good luck!

What RX2fan says about the #1 and #2 tags on the rotor housings is correct. Later housings had "Mazda " logos cast in the tops. Another thing to look at is all the old (pre '73) motors and housings used 19 tension bolts ; eventually later engines went to 18 then finally 17 bolts. These early housings bolts had two or three that do not line up with the '74 and later housings / engines. thus do not interchange. Real early 10A housings had an o-ring recess for every tension bolt , this was dropped in the later 10A early 12A's ( I think maybe 1969-70 ?). I seem to remember exhaust stud spacing issues between early/late years of 10A housings also : early ones had oval exhaust port and later (emission -thermal reactor) ones had a round port like the early 12A's. I have some later (1971) 10A housings ; I can check them if needed to see how they compare to what you have . Hope some of this helps....I have a Mazda R100 Service Manual I'll look into also. Cheers...

Great info, everyone. Thank you!

Is there a demand for pre-'74 rotor housings, irons, and rotors? Are going prices for NOS similar to new parts which are still available for later 12A's and 13B's?

How about demand/value of NOS 10A and 12A 6mm apex seals?

Thank you.

I could use a good 10A rotor housing to finish an engine : any 10A apex seals available ?
PM me if you are selling anything....thanx

There is definitely demand for this stuff. Seems like there's more demand in AU/NZ than US.

Hello, do you still have any 10A engine parts?

Bump .... I am still interseted in 10A parts also. Thanx