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12A is apart but not sure if worth rebuild

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Old Dec 29, 2006 | 06:45 PM
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rx7learner's Avatar
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12A is apart but not sure if worth rebuild

I purchased this engine with the car and it ran good for a few months and blew a coolant seal. I put another 12a with thoughts of rebuilding my old. I just took apart the old, but the outer edge of the housings look worn. Is this normal? Is it worth rebuilding?

Also... If worth rebuilding... the prior owner said that the engine was street ported, and I attached a picture of the port with a ruler beside. Does that look stock?

Thanks
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Old Dec 29, 2006 | 07:53 PM
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Latin270's Avatar
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Those housings do look pretty bad!
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Old Dec 29, 2006 | 07:56 PM
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Housing is toast. Doesn't look like the cooling system was maintainted well at all.
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Old Dec 30, 2006 | 03:14 AM
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Look like a stock port to me.
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Old Dec 30, 2006 | 03:21 AM
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Those rotorhousings are junk for anything except a real economy rebuild. Compression would never be much at all with those.

The port shown is ported somewhat...stock ports are dark in color and have a rough finish, like undercoating underneath a car. They also come to sharp 90* points where the port meets the iron face, whereas most people's streetports are rounded/radiused a little bit where the port meets the face.
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Old Dec 30, 2006 | 11:29 AM
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Just A question. Are those rotor housing so worn that the coating is gone on the outside edge?

Is that Beacause of the apex seals or how did that happen?
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Old Dec 30, 2006 | 04:25 PM
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Yeah... the outside edge all around is prety worn. Fortunately I am not in need of a rebuilt at this point so I'll keep an eye out on flea bay and the 4 sale forum for some that are in good condition... Thanks for the info.

The wear must have had a great impact on performance because the engine I have now is stock port, but performance is much better compared to the old engine (new engine has 70K babied).

I only had it for a few months before she died... so I'm not sure how it got into this condition, but considering the rad was brand new when I got it and the coolant was super fresh... My thoughts are that it did overheat.

Are there any consideration in reusing the irons? Since they appear to be SP'd I would like to reuse those...

Last edited by rx7learner; Dec 30, 2006 at 04:41 PM.
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Old Dec 30, 2006 | 04:44 PM
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Check for pitting around the coolant passages, and warpage. Also for step wear on the iron face on each side (left and right). Irons are usually fine to reuse. Rotorhousings for 85 and earlier models chrome flake severely, even with relatively low miles.

http://www.rotaryresurrection.com/1s...ear_guide.html

The streetport on your irons appear to be conservative, and you could probably either expand them or start from scratch on your originals.
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