i am currently rebuilding a 12a, and i need to find out what rotors are compatible with the one good rotor i have. the rear rotor is not going to be usuable. I am wanting to use the parts from my '83 12a,rotors, flywheel, and counterwieght. my other motor is a '79 12a but only using it for the housings are in better shape. i've noticed all the different markings on the rotors and am wondering what they all mean, several different numbers and characters, some def look japanese. but i guess the most import is the weight difference between rotors as i am sure there are different weights and what not, right?

 

The rule if I remeber right is that the rotors should be within on letter of each other. Theres
letters on the rotors A, B, C, D etc. Could find a link that talks specifically about the labeling.
I think its in the FSM tho.

Heres some informative links:

http://www.mazdatrix.com/faq/rotorwgt.htm

http://www.racingbeat.com/Tech/Tech.Engine.2.htm

Note RB says rotor weight differences are negligible for most applications except very high
performance, high revving motors. So using the 79 rotors should be ok and e-shafts
interchange across 12As. The flywheel or counter weight needs to match the rotors tho.

Heres a good thread with info on rotor mixing.

https://www.rx7club.com/showthread.p...t=rotor+letter

 

there are a couple of IMPORTANT markings on a 12A rotor

on the rotor FACE in the combustion pocket, you will find a F or R, which is front and rear. the 83-85 rotors will also have an N cast in them.

the 76-82 rotors are heavier than the 83-85 rotors and need to be interchanged as an assembly with both rotors and counterweights. preferably as a factory assembly.

the weight letter is stamped PER BATCH of rotors, and is totally useless, as one rotor made in 1979 might be a different weight than one rotor made in 1999.

the rotor faces are also numbered 1,3,5 and 2,4,6 for keeping the seals in the right place.

 

as above but the only amendment would be that any 6 port 12a is essentially s3
( marked N for NA and F or R for front or rear rotor due to the LDR combustion recess )

and that any 12aT rotor instead of N ( for NA ) it has T for ( turbo )

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any s1and s2 rx7 witll have only F and another R rotor
( they must go back in as marked to get the leading deep recess pocket the right way around )

any s3 will have F and R rotors further marked with an N in the bath

any 12aT will be F ( front ) and R ( rear ) and further marked with a T in the bath

 

i think you guys have given me what information i need to know. thanks again guys. cain't wait to hear the old "7" breathe again. and acctually get to get in and raise some hell.....hahahahahaha it is going to be fun.....