1st Generation Specific (1979-1985) 1979-1985 Discussion including performance modifications and technical support sections

Name that 12A mod

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Old Jun 11, 2014 | 06:04 PM
  #26  
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From: https://www2.mazda.com/en/100th/
Originally Posted by diabolical1
that said, i do have a question. i've never worked with carbons before, so do they usually have one or two springs?
one, and the ends are different than the spring for the steel seals
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Old Jun 11, 2014 | 08:24 PM
  #27  
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First of all, I did not realized I looked that weird to make it a mod. (7)
On the rotors, other than the rubber bands and the copper wires, all I can see modified, is the fact that it has new bearings, (stockish, at that)
The paint I did not pointed it out, even thought Ray and I talked about it, since it would not make it any faster or slower.
On the E-shaft all I can see that stand out is the oil passage plug.
This should give me at least 2.5 points!

The engine was build by a Rotary enthusiast mechanic which put some money into the build. Too eager and not very familiar with rotaries, he went on and rev the engine while cold and fused the rotor.
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Old Jun 11, 2014 | 08:33 PM
  #28  
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Good info Carlos, thanks. It's all starting to make sense.

So with that, let's close the contest and declare Jeff the winner with 9 points.

J9 is second with 8 points, Carlos 3rd with 6 points and DB fourth with 5 points.

Honorable mentions for all the guesses.

Here's the full list of the identified mods, together with my guess as to whether they're good or bad (additional comments welcome):

1. carbon seals - not sure on this, but I'll give them a try (does anybody know who manufactured these? They don't look like the ones from Mazdatrix or Racing Beat)

2. FD corner seals springs - good

3. intake water jackets plugged - good, especially if you don't have a nikki

4. ported exhaust - good, more HP

5. ported and polished intakes - good, more HP

6. rotor housings painted silver - good, looks cool

7. irons painted red - not sure on this one, I'll probably go gunmetal or full blown My Little Pony

8. weird guy sitting in the engine bay - good, can't have too many rotorheads

9. custom highly original porting style - good, makes the ports one of a kind

10. no rubber inserts on the corner seals - not sure, did they do this because of the carbon apex seals?

And here are the three that were missed:

1. The engine has 83-85 rotor housings, and 76-82 rotors, a non-stock configuration. This is apparent from the F and R stamps in the rotor faces as well as more subtle marks on the sides, which are specific to the early 12A rotors. I plan to rebuild using the lighter 83-85 rotors.

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2. The apex seal springs are aftermarket, of unknown manufacture. They appear to be made of brass, they are non-magnetic and shorter than the stock springs. If anybody knows who makes these please let me know, I lost one that will need to be replaced; my nail broom was useless.

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3. The eshaft was indeed modified by an over eager rotor head who had just spent a lot of money building a ported 12A. This was a bad idea.

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Old Jun 12, 2014 | 02:09 AM
  #29  
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Ray wow I learned so much from this thread. Good deal.

hahaha-on #7 you should totally do something related to MLP
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Old Jun 12, 2014 | 10:37 AM
  #30  
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From: https://www2.mazda.com/en/100th/
Mazda makes the carbon seal and appropriate spring (which is different). racing beat is probably the easiest place to get them
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Old Jun 17, 2014 | 07:57 AM
  #31  
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Originally Posted by j9fd3s
Mazda makes the carbon seal and appropriate spring (which is different). racing beat is probably the easiest place to get them
Those are Mazda's... look just like mine.
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Old Jun 17, 2014 | 08:50 AM
  #32  
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Thanks, I was guessing RB, which has the aluminum core, but they didn't look quite right, the flat part on the ends of the bottom edge are shorter than the RBs.

Can you tell if the apex seal springs that came in this motor are also from Mazda? And are the RB apex seal springs compatible with the Mazda carbon apex seals?
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Old Jun 17, 2014 | 09:23 AM
  #33  
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From: https://www2.mazda.com/en/100th/
Originally Posted by ray green
Thanks, I was guessing RB, which has the aluminum core, but they didn't look quite right, the flat part on the ends of the bottom edge are shorter than the RBs.

Can you tell if the apex seal springs that came in this motor are also from Mazda? And are the RB apex seal springs compatible with the Mazda carbon apex seals?
RB just resells the Mazda part
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Old Jun 17, 2014 | 09:58 AM
  #34  
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It makes sense that they all would be the original Mazda carbon seals being sold by different vendors, but why do they look different?

Here's the ones Racing Beat sells:



Here's the carbon seals at Mazdatrix:



But the ones that came out of this engine look different from both the Mazdatrix and Racing Beat carbon seals - notice the flat parts at the ends of the bottom surface are longer on the Racing Beat and Mazdatrix units and the Mazdatrix seals have a little right angle in them.

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Old Jun 17, 2014 | 11:08 AM
  #35  
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Originally Posted by ray green
It makes sense that they all would be the original Mazda carbon seals being sold by different vendors, but why do they look different?

Here's the ones Racing Beat sells:



Here's the carbon seals at Mazdatrix:



But the ones that came out of this engine look different from both the Mazdatrix and Racing Beat carbon seals - notice the flat parts at the ends of the bottom surface are longer on the Racing Beat and Mazdatrix units and the Mazdatrix seals have a little right angle in them.

Yours laying there look exactly like my Mazda's I bought 6 months ago.
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Old Jun 17, 2014 | 01:27 PM
  #36  
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I wonder if the ones in the Racing Beat photo are what they look like before they've been trimmed to fit the 12A rotor width?

It seems like that would be a lot to have to take off to fit, looks like a mm or two on each end, but that would explain why the new seals are wider than the ones installed in engines.

Or else the RB photo is just dated and the current Mazda carbon seals have the shorter flat spot.
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