i'm about to start a project. i've begun to accumulate some parts here and there, but before i take any big steps, i want to clear a few things up.

i'll start off by explaining the project, and the information i've gathered so far.

the 13b swap to the miata seems fairly simple on paper. from what i've read, the drivetrain can be set up like this:
-13b engine with an RX7 bellhousing will mate to the tail of the miata tranny.
-The input shaft will need to cut back, but this allows you to keep the PPF and stock driveshaft/rear/axles.
-To mount the motor, buy this subframe: http://m79ea.qxdj9.servertrust.com/S...lts.asp?Cat=98
-Swap the front case on the 13b to the 12a case, which has the engine mount locations on the front, and fab the mounts to the subframe.
-12a oil pan clears the stock subframe, so the V8R one should be no problem.

Fairly straightforward. I want to run Weber 48 IDA's, so no wiring headaches.

the few things i'm unsure about, and can't find more info on:
-what bellhousing specifically will mate to the miata tailshaft

-how compatible the various 12a and 13b parts are. The front engine case from the 12a or early 13b has to be used, because it has mounting points for a FRONT engine mount, rather than the side ones. is this a direct bolt on swap? what about oil pans?

-am i best starting with a 12a, with a carburetor from the start, or buying a 13b, and going from efi to carb'd

 

first of all, that link was great. never knew they existed. a rotary Miata is something that's always intrigued me and i'd love to go for it when my life settles down. so thanks.

anyway, start with a 13B. a 1984-85 13B would be perfect because you already have the front mount setup. however, a 1986-91 would be fine, too. there's nothing wrong with 12As, but 13B parts are easier to get new. the 12A front cover bolts to the '86-'91s just fine. i think there is a small misalignment with the bolts for the 13B oil pan though. if i recall the '84-'85 13B oil pan will solve that. converting to carburetion will be the same for all because they're all fuel injected from the factory. you'll need to find carbs and manifolds on your own.

i don't know the answer to your transmission question because i've never handled a Miata transmission. i don't know if the bolt pattern will fit a rotary or if the tail housings are interchangable with rotary trannies. sorry.

 

I have a friend that has a 13B powered Miata. It has a Holley on it, I don't know if an IDA would fit under the stock hood.

AFAIK any RX7 tranny front half will fit the Miata 5sp back half.