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so I've been in the rotary world for about 16 years now. I've replaced many short blocks with good engines but never jumped into the rebuild world until now. My go to stock port 12a has finally lost life in rotor 1 and I have multiple donors in need of repair that I want to try my hand in bringing back to life. One in particular, is a rebuilt street port that the previous owner attempted a draw thru turbo setup that ended up with it being great in compression at cold start but when warmed up lost power (compression i assume) and we pulled it and has sat since 2012? My 7 is an 85 12a and street port 12a engine origin is unknown but my question is what all am I looking at getting or considering in this? I can get numbers off the engine in the near future and I know I need to Crack it open before investing in parts but I'm looking for any advice from my fellow 7 family.
How many is "multiple donors" ?
Sounds like you already know what to do, find the best parts from the stock of engines you have. If you don't have the tools budget some port work if you have to mix and match housings.
How many is "multiple donors" ?
Sounds like you already know what to do, find the best parts from the stock of engines you have. If you don't have the tools budget some port work if you have to mix and match housings.
From memory I have 5 including this one and a Bridgeport but I think my brother's gonna put that in another fb..... I ran it for years but got tired of street driving it and getting pulled over for noise. Lol I'll have to see what the street port housings look like..... what are the special tools I'll need to have for tearing down and rebuilding?
From memory I have 5 including this one and a Bridgeport but I think my brother's gonna put that in another fb..... I ran it for years but got tired of street driving it and getting pulled over for noise. Lol I'll have to see what the street port housings look like..... what are the special tools I'll need to have for tearing down and rebuilding?
the engine is pretty good, you actually don't need many tools at all. Flywheel socket, 17mm, 19mm, 10mm and a 12mm are all you need.
I rebuilt one of my 12As, with a solid background of experience in tire-changing and paint buffing
The point is if I can pull it off, anybody can. If.you.do.your.research. I bought all THREE of the available "How to rebuild a rotary" DVDs out there.
Best/most expensive was a 3-set from New Zealand ($110)
Best value/bang-for-buck was the $30 Mazdatrix one
Not bad (OK, music: bad) was Atkins @$30 also.
Note all these are "for" 13B builds, but the tech is the same.
These DVDs are STUFFED with little tricks and secrets that can save you time and frustration. Stuff the OE manuals do not begin to address! Quite simply, they saved my Build. Can't speak to the quality or accuracy of the Youtube tutorials. You get what you pay for?
One gadget I was happy to have was rotary-specific tool sold by pineapple racing.com (Rob is a loooong time recognized rotary rebuilder out of Oregon): https://www.pineappleracing.com/cool...estercspt.aspx
This device gives you great insight as to the correct operation (sealing!) of you Build BEFORE you put everything back on the motor and drop it in "hoping it all works"!!
Other one was correct rotary engine mount adapter for engine stands! You need to easily be able to flip block around during assembly, this makes it a breeze on stand.
Also, there are numerous after-market improved parts, starting with better water-jacket O-ring sets (I choose Pineapple's seal kit: https://www.pineappleracing.com/pine...lications.aspx
than stock. Since these are a major failure point, why not use the best?
Likewise tricks (as presented in the video DVDs I noted) is, for eg, use the later-style corner-seal-springs. Made for FC+, but completely backward compatible to 12A (as many parts are).
oh i also like to use the FD service manual, the measurements are different, but the rebuild section is expanded a lot vs the FB ones, Foxed.ca - Mazda RX-7 Manuals
and then there is a specs page in the back of all of the manuals, and its got the measurements and torque specs together which is nice
Awesome advice and thanks a lot guys! I was just looking thru my service manual actually just before checking this and noticed it was a bit vague. And am I crazy or have I seen people stacking the engines starting at the rear when the manual starts at the front? Is this just me or is there a preference? And noticed this in my Pic..... 12b? Lol just referring to the beehive era or a misprint? I've never heard of them referring to a 12b.
Awesome advice and thanks a lot guys! I was just looking thru my service manual actually just before checking this and noticed it was a bit vague. And am I crazy or have I seen people stacking the engines starting at the rear when the manual starts at the front? Is this just me or is there a preference? And noticed this in my Pic..... 12b? Lol just referring to the beehive era or a misprint? I've never heard of them referring to a 12b.
internally they were thinking about changing it from the 12A to the 12B when they revamped it in 1974 (?). the redesign from the early motors was a really big one
Wouldn't that make inserting the tension bolts unnecessarily awkward?
Now that you mention it.
OK, may have to rethink that remark! Defer to peeps with more recent builds (mine was 6 yrs ago...fog of age?).
Now seems to me the engine-holding bracket has to mount on the AC bolts of the front housing to allow for attachment to eng stand, thus start build from fr iron, then stack to the back?
Haha my bad! And now that is painfully obvious. Lol I wonder why in my 85 service manual they still refer to it as a 12b then? Oh well...... great info here guys and thanks again! Once I get it tore apart I'll post pics.
what are the thoughts of the status of this engine? See some troubling things so far in the rear section. And tips on removing the center iron? And do these look like street ports? Thanks members!
Those spots are "OK". Just make sure there are no high spots. If there are take them down but don't mess up the chrome by using sandpaper.
For getting the front iron off, yes the front bolts needs to come off. The issue is that the can may be stubborn and you might need to put the flywheel back on to be able to hold the e-shaft.
Those spots are "OK". Just make sure there are no high spots. If there are take them down but don't mess up the chrome by using sandpaper.
For getting the front iron off, yes the front bolts needs to come off. The issue is that the can may be stubborn and you might need to put the flywheel back on to be able to hold the e-shaft.
will do...... just talked to my dad "who has been itching to tear down and rebuild a rotary since I was a teen" and he is a mechanic so I'm driving over the left over parts to him tomorrow where he has all my spare parts and heavy duty tools. I loosened the front iron but still not enough room without removing the drive pulley. And where can I find the stock intake and exhaust port sizes to compare to these? I've searched but can't seem to find actual measurements..... just port templates.
How can I assess the oil seals and their reusable potential? I don't think this engine has many miles on it...... it was a draw thru turbo attempt and I'm thinking it had been pushed past its corner seal limits...... and going solid corners for sure.
will do...... just talked to my dad "who has been itching to tear down and rebuild a rotary since I was a teen" and he is a mechanic so I'm driving over the left over parts to him tomorrow where he has all my spare parts and heavy duty tools. I loosened the front iron but still not enough room without removing the drive pulley. And where can I find the stock intake and exhaust port sizes to compare to these? I've searched but can't seem to find actual measurements..... just port templates.
The pulley just unbolts but you'll need to take the pulley hub off also. The big bolt needs to come out and it also has a key that keeps it on the e-shaft.
03-09-21, 10:08 PM
