can you use 12a ends with 13b rotor housings?

[dubber91]

to change from 6 to 4 port?

Just a crazy idea...

Steve

[MikeLMR]

I don\'t think its a straight swap, for a start Mazda moved the o ring groves from one housing to the other after the last of the 12a\'s so anything later will be the wrong way round.

[kev-yorks]

There now machining 13b housings down in Aus to suit 12a plates and rotors as there are no more new 12a housings about. So it may well just be a case of machining a "o"ring groove to suit. Best bet is give one of the engine builders a bell.
Kevin

[drutin]

howzit

depends on what 4-port or 6-port engine your talking about :0

the later 2nd generation rx7 series 4/5 and 6-8 use the water seals in the side plates
but the old generation 1 rx7 series 1-3 and rx3,4,5 and old cosmo 13B\'s had the water seals in the rotor housings, which you could use 12A side plates especially the tallport center plate in the 13B as as far as im aware the only 13B to have a tallport motor was the rx5 engine from factory not rebuilt by someone
the jap spec rx7 series 2-3 and hb cosmo had old type water seal 6-port engines

so you have to use side plates/housings with the waterseals in the same place to interchange 12A/13B housings

unless as said you get the rotorhousings/side plate water seal groove machined $$$$$

later

[dubber91]

i have a 1988 13b.....what series is that?

Steveo

[drutin]

howzit

its a series 4 rx7, generation 2, FC, it will have the water seals in the side plates
you can use turbo series 4 or 5 side plates front and rear
to get your 4 port configuration,
hope that helps ?