Can anyone tell me about the 12b engine? I am in the Army and stationed in another country. My wife found a parts car and my father in law said it had a 12b in it. My car has a 12a. Im still pretty new with rotary engines and anything yall can tell me will be a big help.

no such thing as a 12b, its either a 12a or a 13b

Thats what i thought thanks for the info I will go pick on my father in law now.

Just to nitpick, the '74-'78 12As were known internally to Mazda as the 12B.

yes. as far as i understood it, all 12As before 1974 were 12As and everything afterwards, including the Rx-7 engines, were 12Bs, even though they were officially called 12As.



and, by the way, i think it has something to do with the different seals used before 1974.

however, just to be clear - as far as i know, there was NEVER an engine that was marketed or stamped as a 12B.

No, it was never marked as such. There could have been different seals, but the main difference is that the later engines ditched the twin-dizzy design for a single distributor.