Hi Paul,
        I'm enjoying following along with your current threads!!
        Hope you don't mind me chiming in here again to ask another newbie
        question:

        I've been slowly acquiring S5 NT (9.7 : 1) rotors for my 20B NA
   project
        (much cheaper that RX8 rotors). I had 2, and just received the
   3rd one
        today. I've been trying to be careful to make sure I get rotors
   with
        matching weight code stamps, but the one I got today is
   different. Can
        you help here? I hope you don't mind me including pictures!! I
   tried
        to make the files small. The first 2 pics are the rotors I
   already had,
        and they show a "C" along side another weird symbol (kinda looks
        like a 7).

        The next pic is the rotor I got today. It shows a "C" along side an
        "E" :
        My question is.......Is it OK to use all these rotors together? Are
        these all S5 (9.7 : 1) rotors? Is this last rotor a weight code
   "C" or
        "E" ? What's the other symbol of Letter mean?

        Thanks again for all your help and knowledge!!
        Don

         From what I gather you can't mix and match weight codes.
        I think you need to have it balanced by an experienced
        rotary engine balancer. The rotors must be balanced
        about their center point and matched with all the other rotors
        for weight and then the counter weights adjusted
        for the exact weight of the rotors. There is a guy here in
        So Cal that does it.

        Rotor weight codes.
        The only thing I can find is this.
        http://www.rx7club.com/showthread.php?p=1309602#post1309602-

        I'll forward this to Jim Mederer. Hopefully he will have time
        to help as he gets the really hard questions :)

        Paul Lamar ...No rotor no motor.

   Hi Paul,

         All 3 rotors are "C".  The "E - like" character may be Japanese or
   may have some other meaning, but it isn't the weight.  In recent years,
   all or nearly all rotors are "C" thanks to improved manufacturing
   methods by Mazda.

   Jim Mederer


   Thanks Jim.

   Paul Lamar

Thanks Paul and Jim!!
From what you've said, I gather that I'm OK to use all 3 of these
rotors.  I was planning to have the rotating mass dynamically balanced
anyway.  I was mostly concerned about the "E" mark on that one rotor.
It is a DEFINATE  "E" , and not a weird symbol like on the other 2
rotors have.  Was there ever a rotor made with weight code "E"?  If so,
it seems weird that they would put both a "C" and "E" on the same rotor.
These are all supposed to be from Series 5 non-turbo engines so I hope
Mazda's manufacturing processes were good back then!!!
Thanks!!
Don


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