Old 12a Questions
01-06-2005, 08:04 PM
#1
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Join Date: Jul 2004
Posts: 270
I have had an old 12a given to me, and when i got it i looked at it and it had a spot for 2 distributers, well i already new they made thoughs before but all the housings looked much differnt. so as i am taking it apart i relize first that it has a lightened eccentric shaft and secondly that it has big *** 6 mm 1 peice apex seals and 2 side seals on everyside. I thought that they only had these 6mm apex seals on 10a's, then i took and apex seal out and weight it and it only weights 7.5 grams it feels super light, what are these made of?? Also wondering since they are so think and 1 peice, would they be good for a turbo engine, the my other question is where can i buy side seals for them?? thanks, mike
01-07-2005, 10:04 AM
#2
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Join Date: May 2002
Location: California
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they are normal carbon seals. they wont hold up to a turbo and it doesnt matter because you cant buy them anyways.
they are no longer available from mazda, and i know someone who bought some from ebay, and they were bad from sitting in the box for 20years.
good news is that you can put 74-85 12a rotors in there and have a runner
they are no longer available from mazda, and i know someone who bought some from ebay, and they were bad from sitting in the box for 20years.
good news is that you can put 74-85 12a rotors in there and have a runner
01-07-2005, 10:15 AM
#4
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Location: California
Posts: 22,465
the side seals are normal, 1011-23-whatever's
those motors were made for the rx2/3 until 74 when the steel apex seal single distributor engines came out.
these motors are rare now because in the scheme of things they suck, theres a lot of problems with electrolisis (your rotor housings prolly have holes in them), the carbon seals dont work very well. the steels arent nitraded etc etc.
basically its a conversation peice now, although they do have a larger exhaust port than the 76+ motors
https://www.nopistons.com/forums/index.php?...type=image/jpeg
those motors were made for the rx2/3 until 74 when the steel apex seal single distributor engines came out.
these motors are rare now because in the scheme of things they suck, theres a lot of problems with electrolisis (your rotor housings prolly have holes in them), the carbon seals dont work very well. the steels arent nitraded etc etc.
basically its a conversation peice now, although they do have a larger exhaust port than the 76+ motors
https://www.nopistons.com/forums/index.php?...type=image/jpeg
01-07-2005, 06:38 PM
#5
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Join Date: Jan 2004
Location: Central Ohio (Hebron) Zephyrhills Fla.
Posts: 1,322
Originally Posted by mike_rudy' date='Jan 6 2005, 06:03 PM
I have had an old 12a given to me, and when i got it i looked at it and it had a spot for 2 distributers, well i already new they made thoughs before but all the housings looked much differnt. so as i am taking it apart i relize first that it has a lightened eccentric shaft and secondly that it has big *** 6 mm 1 peice apex seals and 2 side seals on everyside. I thought that they only had these 6mm apex seals on 10a's, then i took and apex seal out and weight it and it only weights 7.5 grams it feels super light, what are these made of?? Also wondering since they are so think and 1 peice, would they be good for a turbo engine, the my other question is where can i buy side seals for them?? thanks, mike
Another problem is that the rear iron bolt pattern fits the early smaller diameter bell housings.
Good for restoring an early RX-2 or -3.
Put it on the Vintage Rotaries web page. Maybe somebody needs some of those pieces. We used to grind down the fat carbons to fit 3MM slots to get cheap (free) racing seals. As for using the pieces to build much power, you can do much better with the later pieces.
Lynn E. Hanover
01-08-2005, 12:55 PM
#8
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Join Date: May 2002
Location: California
Posts: 22,465
Originally Posted by mike_rudy' date='Jan 7 2005, 05:42 PM
Since i am the one that started the lightening of many parts thread now i am wondering if i can use the lighten eccentric shaft with counter weight on a newwer model of 12a? Thanks, Mike
yes you can. make sure the shaft is straight, its olde`
01-08-2005, 12:57 PM
#9
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Join Date: May 2002
Location: California
Posts: 22,465
Originally Posted by diabolical1' date='Jan 8 2005, 10:50 AM
could you post some pictures of the rotors and 6 mm seals, please? i've never seen them ...
https://www.nopistons.com/forums/index.php?...&album=43&st=45
