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Basically I'm at a crossroads. I have an 85 GSL with 110K miles on the clock on the original 12A. I've done a compression test and am getting 90+ on all the rotor faces. The goal is a reliable and fairly quick street car resto-mod that's daily drivable for a while. I know 12A housings are hard to get so I'd like to either preserve the existing housings for a while longer or rebuild the engine as a 13B but ideally I would like to keep the 12A in as good a shape as possible.
Here's the question: is it worth tearing the current running engine down and replacing apex seal springs (maybe even the apex seals) and doing a little porting and putting it back together? Or should I just wait until it starts losing compression to tear down and rebuild? My thoughts are that if I rebuild it now and get ahead of the wear I might be able to get a longer life out of the rotor housings but I'd like some thoughts on if that's a realistic expectation.
is the car stock? if so, why not start with a full exhaust system and see what that does for you? it will wake the engine up significantly. if that doesn't satisfy your desire for a "fairly quick street car", then you can consider porting, and for me, i would still probably leave THIS engine alone. what if you end up porting and not liking it? i doubt the engine you would replace it with would be in as good of shape as your current one. i would get a second engine - whether 12A or 13B - and build it.
Yes I think that is some good advice. Opening up your 12A to replace a few parts.. I don't think will get ahead or reduce wear rates. New seals and springs might even accelerate the wear, maybe some one more experience could comment on that.
I had sourced a second engine and had that rebuilt.. streetport 12a, like new housings (not sure where they came from...), all new seals, springs, gaskets, and lapped + Nitrided irons. It is a night and day difference to a stock 12A.
In the mean time, I pulled my original 12A apart... I had it stored for a few years and figure why not open it up to see how things are. This is my cars original 12A.... 60k miles or so. Maybe bad luck? I have no reason to think the engine was abused. Cooling, oil system, bearings all look great.
So don't open up a good 12A because you might not like what you find! Only option from here is build up a 13B...
Looks good from this angle... Pretty clean right? Wow.
Last edited by tommyeflight89; 11-01-21 at 05:25 PM.
is the car stock? if so, why not start with a full exhaust system and see what that does for you? it will wake the engine up significantly. if that doesn't satisfy your desire for a "fairly quick street car", then you can consider porting, and for me, i would still probably leave THIS engine alone. what if you end up porting and not liking it? i doubt the engine you would replace it with would be in as good of shape as your current one. i would get a second engine - whether 12A or 13B - and build it.
Yes, the car is currently totally bone stock. I'm going through a winter "stage 1" sort of mod/rebuild session to fix the lingering issues (leaking rear diff seal, clutch throwout bearing noise) and upgrade replace things like shocks, springs, and suspension bushings. I'm also planning on installing an RB streetport system and doing a partial delete of the rats nest to get rid of the things that don't work and aren't needed like the shutter valve (was jammed open) and the throttle pusher (no A/C anymore).
The problem I'm running into with getting a second engine to build is just availability. There aren't a ton of RX7's in Alaska and the ones there are are priced like "I know what I got". No parts cars to speak of so that leaves shipping an engine up for substantial cost and hoping it's close to usable.
You're right on though, I may just leave well enough alone for the meantime and work on the rest of the car. My main hope was that for the cost of a seal kit and springs I could keep the wear on my existing housings to a minimum but it sounds like that's not a guarantee.
11-01-21, 02:46 PM
