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12a Rotor Housing Differences Question

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Old Mar 12, 2007 | 10:39 PM
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12a Rotor Housing Differences Question

Hey Guys,

I found this pic in my rotary pics folder and noticed something I hadn't really remarked before. Look at the top of the housings. Some of them have a square chunk of metal sticking out and some have an H-shaped chunk of metal.

For one I dont' know what this is for. I've got a pair of rotor housings here in the basement with the square chunk and really I can't see the purpose.

But what's the difference between the housings with the square and the ones with the H?



Jon
Attached Thumbnails 12a Rotor Housing Differences Question-img_0055.jpg  
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Old Mar 12, 2007 | 11:01 PM
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The ones with the chunk instead of the H are early model housings. Meaning before the 7 motors. What the internal difference is I can't recall. I'm sure that trochoid may know.
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Old Mar 12, 2007 | 11:03 PM
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The chunk are old style. The H was to reduce weight probably. They did other things to the casting for weight reduction, so it kinda makes sense.
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Old Mar 12, 2007 | 11:06 PM
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There was a change in '83 for the 12A turbo engines. Check out the bracing in the water jacket between tension bolt holes. The old style had bracing on the outside. The early RX-7 housings didn't have much bracing. The later RX-7 housings had an extra brace between the tension bolt holes, as did the GSL-SE rotor housing you have sitting there. And you think trochoid may know this? Puh-lease.
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Old Mar 13, 2007 | 07:30 AM
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damn... I may have to snap some pics of my "new" rotor housings for a "identify these" thread 'cause they've got the chunk, but they were supposed to be S2 or S3 housings.

Not that I think it'll make that much of a difference, but with all the work I'm putting into this engine, why choose the "lesser" housings.

Jon
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Old Mar 13, 2007 | 12:31 PM
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And apparently I didn't because I was thinking the blocks were the later ones, lol.
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