Understood. Do you think I should just go with the Atkins master rebuild kit? Since this is my first build and might not be super perfect?

 

It really depends on budget and desired outcome. One big caveat to the desired output is the condition of the used parts. You can reuse apex seals if the budget is low, but they have to be in spec.

Here is the rebuild criteria from Mazda. It's for the 1979 but still applies to all newer 12A engines. I'm not an experienced engine builder like others on the forum just going off years of collected knowledge.

I would agree that since this is a new experience for you, I'd treat this engine as a learning experience and if parts are in spec, go with those.

Rotary Engine Overhaul Criteria and Criteria for Replacement of Parts

 

I have cleaned the rotor housings with a simple green + water mixture. I used compressed air to get moisture out of the oil and coolant passages after cleaning, but I wasn't really able to scrub in those passages.

Is this a fine way to go about cleaning my essential parts? I do not want any flash rust. Should I switch to purely simple green?

Looking for general advice on cleaning the motor and next steps towards the rebuild as it is a bit overwhwhelming at this point. Thanks.

 

After getting lots of opinions on my previously posted housings, it looks like the motor likely wouldn't last past 40k miles.

So I got 2 new housings:
- One is completely perfect. No chrome flaking, electrolysis, and chrome thickness is in spec.
- One does have 2 minor chrome flaking sections that I have pictured. They do not feel nearly as deep as my other housings, and the seller is confident that it can last 80-100k. (I hope so, but will keep my next best housing around to swap in just in case)

For each the 2 Rotors:
- I have soaked them in Berryman's carb cleaner, pressure washed, and dried using compressed air and a space heater.
- They look great to me but let me know if anything looks off.

Planned Next Steps:
- Cleaning Irons, checking wear
- Checking all seals for re-use (*HELP*)
- Getting Flywheel resurfaced at a shop this week for $80
- Locking in a good clutch, and aluminum radiator to buy (*HELP*)

Need Help:
- Seals:
- Which seals should I consider reusing? I believe the corner buttons?
- Is there a thread/guide other than the FSM that can help me easily understand how to check tolerance + fitment for all my current seals?
- I'm planning to go with an Atkins master rebuild kit but am wondering if it will be smarter to attempt to reuse any in-spec seals and then individually order the seals/gaskets that I actually need?

- Clutch + Radiator
- I'll be reusing the OEM Flywheel which is getting resurfaced this week. Any good suggestions for a solid OEM+ clutch I should go with?
- I was reading up on rads for these cars, and it seems like a ~$100 ebay no-name aluminum rad might actually be a smart move? I don't want to reuse the OEM rad as I'd like to eliminate heat soak. Is it worth going with a brand name rad or should I just run a cheaper ebay one?

Thanks for reading and all advice.


Housing 1

Housing 1

Housing 1

Housing 1

Housing 2

Housing 2

Housing 2

Housing 2






Simple green + brake cleaner?

 

Hey everyone - Update on my 12a build, and looking for some final advice before attempting the build.

Final parts coming:
ARE150 Atkins Rebuild kit - Ordered 3/16 and will have the kit within a few days.
Exedy Stage 1 clutch kit - Ordered 3/16 and will arrive soon.
Hylomar - Arriving tomorrow

Iron step wear has been measured and all 3 are in spec.
They have been degreased, and old gasket material cut down with a sharpening stone taking care to not touch the chrome surface.
BUT:
- I do see this one streak on surface of the rear iron that is a bit worrysome. Even after wiping with degreaser, this streak appears. My friend pointed out that it could be a micro-crack or a crack under the surface?
- I'm thinking of just sending this as it looks relatively fine and my other rear iron failed the step wear tests.

Any advice against the iron or any general advice before I toss this 12a back together?

I'm planning to follow this YouTube video for my build:







Front Iron

Middle Iron

Middle iron

Rear Iron

Rear Iron STREAK MARK w/ Flash

STREAK MARK up close no flash

Parts Storage

 

First off, awesome work... especially doing it in your living room!

I'm no expert in assessing the quality of your parts, but I do think a crack is unlikely. That said there is magnetic crack detection, maybe a local machine shop could do that for you?

 

thanks for the video.

I ended up just sending it and am hoping its not a crack lol.

 

Finished product minus exhaust manifold







Well almost exactly 5 months after buying the car, I've finally rebuilt the entire 12a with all accessories mounted (besides exhaust manifold/carb/oil pan)

Getting really excited to drop this thing in and fire it up.

Questions I've got now:
- Should I toss some blue or red loctite on the pressure plate bolts for this motor? (Exedy Stage 1)
- I'm planning to run Oreilly's conventional 20w50 that I used for assembly as my oil for the first 500 mile break in. Is this advisable?
- Need help deciding pre-mix:
- I have a new bottle of Lukas 2 cycle sitting around, is this fine or do I really need to get Idemitsu/another brand?
- I was told to run 0.5 oz per gallon, I believe as a suggestion to extend the life of my worse housing that has the small amount of flaking on the edge. Is this advisable? Or should I just go for 1 oz per gallon?

As always thanks for the help everyone.

 

Took a lot of trial and error to get the engine mated to the trans. Ended up having to put the car in 1st, and roll it forward slightly to allow the input spline the perfect alignment.

Got these bonzai poly mounts in place as well.

Will be bolting carb/ac/rad up tomorrow, and preparing for a first start.

 

The 12a is fully installed, and running very well. I have put roughly 90 miles on the car over the past few days. - Keeping it to 4k maximum.

Time to move on to paint correction, and fixing rust.

Thanks to everyone who helped me out. The car is a blast to drive, even with only half the rev range.

Final question: How high will my rebuilt 12a safely rev to when broken in? A dude told me he had 4 FBs and had them revving to 12k.

Would I be able to achieve 9k ish on my stockport setup? And yes I know it doesn't really help the powerband to press past 6 or so.

 

Great work, you should be proud.
Edit: 12K RPM is ridiculous to imagine on a stock engine. To get that kind of number people do all sorts of stuff like balancing rotors and any of the rotating assembly, hardening gears, and reinforcing the long studs. I'm sure there's more.

 

Ah, high revving.... I remember when I first got my FB with electronic ignition. A major step up from my previous SA that had points.

I revved that FB to the freaking moon for like a month. Then I spun a rotor bearing.


Oil pressure keeps the revs down more than anything. Keep it under 9k.

 

Hey everyone -

So my OEM Beehive is leaking coolant, and needs to be swapped out. I just watched the RAD Potential oil cooler video and got a bit of a crash course, but have some questions.

Parts I think I need:
- <!--td {border: 1px solid #cccccc;}br {mso-data-placement:same-cell;}-->Back side of motor oil fitting port - RAD Potential says get stainless steel metric fitting that converts to a -8 AN.
- <!--td {border: 1px solid #cccccc;}br {mso-data-placement:same-cell;}-->Front side of motor fitting is different, need one in that size that also coverts to -8 AN
- Braided soft lines for running from motor to cooler and back.
- One female cap for coolant T
- One male cap for coolant on passenger side firewall

Are there any full kits online you guys can recommend or terminology I can ask for at the Hardware store near me for those fittings?
I'm leaning towards just grabbing a budget ebay cooler as it seems it should be way better than a stock leaky beehive, but want to make sure I do this clean and the right way.

 

A hardware store won't have what you need. I used -10AN when I converted my beehive to a front mount. There are a few of us that have spare beehives. If your hardline is good use it. it will outlive any braided -10AN. I'll post more when I can after work. II know there others that can answer this though.

 

Okay, my hardline is good. Are you suggesting swapping a better condition beehive on to the motor could be ideal then?

I guess that might actually be a bit easier and cheaper, but I expected the aftermarket oil cooler too improve the cooling significantly over stock.

I appreciate the info and look forward to hearing more about the best move I can make

 

There are a few things to think about when going to a front mount oil cooler (FMC). I like theFMC better, but the 12A beehive does work well.

Things to think about. I'm not trying to sway your decision, but her goes.

All in, you might be between 500-600. Another alternative is to use a second gen FMC. I just don't like using someone's old rad or coolers.

A used beehive with line can cost $50 + shipping. The issue is the cooling lines. I don't think they are available any longer and it's one more failure point.

1. Cost. The front mount will cost more
2. If you can find a factory one, it would be cheaper, but I don't like the factory front mount design because the input/output bungs can crack. A lot of this is because folks overtighten them to fix a leak.
3. The FMC has an internal T-Stat that lets the oil come up to temp faster with a bypass. Aftermarket ones do not come with a T-Stat so an external one needs to be added. Earl's make one (~ $200).
4. A good aluminum FMC can cost $250 and up. Don't get a cheap eBay one.
5. Next is designing the FMC mounts. Since you have a 1984/1985 you may need to get a shorter radiator depending on how mount it. Search the form and find the FMC that uses angle iron and exhaust clams to mount to the round crossbar
5. The -10AN lines and fittings. I like the nylon braided. You'll need these (~$150)

• M18 x 1.5 to -10AN: This adapter is required for the rear housing (rear iron) of the engine.
• M16 x 1.5 to -10AN: This adapter is required for the front cover of the engine5.

 

Given the low down, I am leaning towards swapping my beehive with a good condition one as I am finishing up college and funds won't allow 500-600 for the front mount cooler at the moment.

Is there anyone you know on the forum that would sell me a good beehive to swap onto my motor? I will check ebay in the meantime.

Appreciate the help.

 

I have one or two. Don't by one till I check my stash.

 

One thing to check. Make sure it isn't the beehive oil rings. This is a common problem with age and the heat. They flatten out because of pressure being clamped and heat. You will need new ones anyway of staying with a beehive.

 

You beat me to it.

T stat is important here. Unless you live in a climate that's hot all the time and don't mind a few minutes of waiting for oil temps to rise.

Back when I was in the first gen game I mounted mine right in front of the radiator. I don't think the bottom mounted ones don't mix oil/water temps too well.


I run a beehive on my car, but I don't have enough data to advise for or against using a water cooled oil cooler or not. Air to oil is all I've ever used.



To get off topic, on my car I think I'm going to go hybrid and put a tstat restricted air oil cooler in line after the oil water behive. Double cooling effect

 

You can take your fittings off the beehive and a hose shop should be able to make some new lines for you.

You will need the FMOC and hoses that come out of it to get the lines made for that part.

You will need an oil pedestal for a Mazda.


If you go the A/N route you can use the fittings from the beehive and get the hose shop to mate them to A/N lines.

 

Some data on beehive o-rings from when I replaced mine:

https://www.rx7club.com/1st-generati...shers-1163160/

 

Leaky beehive replaced with a better one. Still have a leak from shat seems to be either the rear iron or beehive pedestal. I plan to pull my "new" beehive asap as well as the pedestal to check it out.

Please feel free to give me a guess based on first glance of the leak location. I do think there was the slightest possible suspicion of a miniscule crack on one of the irons if you guys remember from earlier in this thread, but it was never confirmed.

Video:
https://www.reddit.com/r/RX7/s/KU122lLLkS

 

Mr. FBrick, I saw your pic with the mounts which I think are Banzai and I had to go look at my car to check. Then I searched for install instructions and it took a while.
https://www.banzai-racing.com/produc...o_09-19-17.pdf

I have actually wondered if it would make any difference though as I had mine the other way at first. But I am still days away from start up and cannot find time to finish.