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Index > Engine/Drivetrain > Thread: Which rotor housings?
Thread: Which rotor housings?
Klaus43


Rotorhead
Posts: 1259
posted January 15, 2004 10:25 AM

Which rotor housings?

OK, here's a topic of interest to any of us still contemplating the resurrection of our old 4-ports... :(thanks for the inspiration, Bill!)
Given that 'our' engines were only sold here in the US for five years, 1974 thru 1978... and that it might take from 5 to 7 cores to find enough good parts to build one...

1.) What are the definitive limits of options for rotor housings that can be used with our oldschool internals, and what, if any of these, are still available?

2.) I'm speculating that the so-called 'j-spec' NA 4-port 13B's were built, and delivered, elsewhere in the world thru a much later date... just how recent, and widespread were they... and might rotorhousings (and, perhaps, other useful bits) still be source-able for these engines?

Part numbers/source codes with which to call Japan, anyone?

       
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Jeff20B


Moderator
Posts: 661
posted January 15, 2004 01:57 PM

I have a set of 13B rotor housing from '81 or so. They were probably from a Luce or something.
____________
'74 REPU
'76 Cosmo
'77 MG Midget 13B
'81 RX-7

       
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Klaus43


Rotorhead
Posts: 1259
posted January 16, 2004 12:13 PM

They're not NOS, are they?

I figured the 'j-spec' 4ports were likely manufactured/sold thru until at least '85...

       
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rotarydave


Hauling
Posts: 108
posted January 17, 2004 12:08 AM

the j-spec housings usually came from a 6-port type engine mazda did use the same water jacket seal for all of their housings up to 86 so any of the 13b housings from 74-85 can be used but they have to be a pair from the same type engine as some had slightly different positioning for plugs and port sizes. all of the j-spec rotor housings need the exhaust ported as they are smaller than US-spec

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Klaus43


Rotorhead
Posts: 1259
posted January 17, 2004 12:42 PM
Edited By: klaus42 on 17 Jan 2004 12:43

Not to mention...

Which years/ versions had the plug-restrictive 'eyebrows' cast into 'em...?
Then there's the smaller intake porting on the j-specs as well...
I was more curious about any and all NA 4-ports... though I realize that for the rotor housings it makes no difference.
About different plug positioning I had no idea! Now I'm really curious...

       
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rotarydave


Hauling
Posts: 108
posted January 17, 2004 08:16 PM

there was a major difference in the timing position between 74 and the 76 styles i don't think it was that severe between the later ones though, as for the cast irons use 12a they are a dime a dozen you can get a core from a wrecker for 100 or less, I like them and prefer them because of the microporus plating that was used on the later stuff it seems to last longer. not to mention that it is newer. The last 4 port 13b i saw was about a 81 and that was at an engine house and it was totally different and would not have been usable to us as it has a torque converted 5speed the rear cast iron is different, also as you alluded to the intake ports for most of the jspec motors are tiny compared to ours.

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Klaus43


Rotorhead
Posts: 1259
posted January 18, 2004 10:12 AM

One of the reasons for my asking,

or rather, perhaps, three of the reasons...: I've owned three rotaries powered by various incarnations of these j-spec 4ports... and for all their (potential) drawbacks, they were realatively economical, and totally reliable, inexpensive used engines. (In all cases they happened to come with the car/truck in question.)
Not that I wouldn't rather have a different configuration, but as far as perfectly usable 4port 13B power on a shoestring went... they worked.

       
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