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

Prob a dumb question

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Old 03-21-13, 08:31 PM
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Prob a dumb question

Is it possible to take a running 12a apart then port it put it back together with out replaceing seals?

Thanka shane
Old 03-21-13, 08:45 PM
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The short answer is no.

There are exceptions, like if it was recently rebuilt. If it has any type of mileage, you would want at least a seal kit. They run ~$150.

Now if you’re going to go through the process of rebuilding a 12A, and it has a decent amount of miles, having two good rotor housings is questionable. Along with this, there are wear parts that need to be measured to ensure they can be reused. Don't count on being able to do a cheap rebuild.

In my opinion, If the engine is a good runner don’t do anything with it and enjoy as is.
Old 03-21-13, 08:48 PM
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premix, for f's sake

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Yes, you can re-use the rotors seals, if you really really want to. Is it smart to reuse them? No. You will need to replace the seal springs, o-rings between the housings and the basic gaskets, minimum. Honestly tho, if you are gonna take the time to pull and engine out of the car, tear it apart, port it, then rebuild, its much more labor effective to just spend a little extra now and replace at least the apex seals, and measure out the side seals and corners seals. If you just port a worn engine, reuse worn parts, you will never see a worthwhile benefit for rebuilding it in the first place
Old 03-21-13, 09:37 PM
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Ya its good running i just want it ported ... And i was t sure if tearing it open and port then closeing it would work... Lol but i guess not ... Ill run it till it dies.
Thanka shane
Old 03-22-13, 11:33 AM
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yes, but you need the Oring set. although while you're in there, you should measure stuff, and replace anything that's worn
Old 03-22-13, 02:14 PM
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Gotta remember, "Seals" have a lot of different meanings on a rotary, depending on who you talk to.

Can mean:
1) The special rubber o-rings that seal the inner and outer sides of the water jacket all the way around the housings; these generally cannot be re-used on an engine that has run for more than a couple minutes. These are what KC-REPU's probably talking about, & possibly J9fd3s. Think of them like gaskets - once you seal up and heat them, they're not going to be reuseable.

2) The hardened metal seals and springs that provide for oil control and compression on the rotors - the "hard seals." side, corner, apex, and oil-control ring seals, and the springs for each. These expensive lil guys are absolutely reuseable if 1) they are within tolerance and undamaged, and 2) you keep careful track of which came out of which hole or slot on which rotor, and put them back where they came from - because they 'wear in' with engine break-in and won't seal as well if you move them around. These are probably what Sgt Stinkfist is talking about.

3) The specialized elastic "soft" rings that go in the grooves of the hard oil-control rings. They look like giant o-rings, but they are made using specialized compounds (Mazda OEM) or Viton (Atkins.) you usually don't want to re-use them even though they are pricey, because they are a wearpoint that eventually need replacement anyway in order to maintain oil control. Possibly what J9fd3s was referring to.

If you tear down a good-running motor, you always need a seal kit (water-jacket o-rings, as well as the gaskets and small o-rings needed to assemble the keg), you SHOULD replace the oil-control soft rings unless they only have a few hundred miles on them, and you replace any hard seals and springs that are damaged, worn close to tolerance, or that you can afford to in order to move further back the date on which they wear out.

That help?
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