Welcome to the 1st generation RX-7 (and other earlier models) section of the site. I wish to offer assistance to all rotary enthusiasts with their cars, however I must admit that I don’t do much 1st gen work, and I do not have as much intricate knowledge of them as I do the 2nd and 3rd’s.
Part of the reason for this is that there are very few still on the road that people actually care about, so not many come in for service, thus I have less experience dealing with them. Another part is that the engines are quite different from the 86-95’s which are so much more common…the coolant seal grooves are reversed on the older engines, and most of them are carbureted instead of fuel injected (which I am vastly more familiar with). Finally, the biggest reason is that it’s hard to find a useable core to build from with the pre-85 engines.
Since I reuse housings and most parts with my rebuilds, this presents a serious problem. Please visit the technical section and read the writeup for “rotorhousing wear guide” for a visual explanation of the differences in the older and newer engines, and why it’s hard to rebuild the older ones with used housings. Also click above for info on 12a and early 13b rebuilds and availability.