12a rebuild help and suggestions
#1
12a rebuild help and suggestions
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.
#3
#5
52mm socket for the flywheel nut is the only rotary-specific tool I can think of right now.
Check out Aaron Cake's RX-5 restomod vlog, he does a complete teardown and rebuild:
https://www.youtube.com/watch?v=W1MX...65998D&index=4
Check out Aaron Cake's RX-5 restomod vlog, he does a complete teardown and rebuild:
https://www.youtube.com/watch?v=W1MX...65998D&index=4
#6
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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?
#7
RX HVN
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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).
Good luck-
Stu A
80GS
AZ
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).
Good luck-
Stu A
80GS
AZ
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Maxwedge (03-12-21)
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#8
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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
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
#9
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.
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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.
oh and you're crazy
#13
RX HVN
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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?
Apologies may be in order...
;P
Stu A
80GS
AZ
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?
Apologies may be in order...
;P
Stu A
80GS
AZ
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Retoroka (03-19-21)
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it does look ported. that rotor housing is pretty mint.
#19
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.
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.
#20
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.
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.
#22
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you can measure them! i posted a link to the FD manual, and it covers that stuff pretty well
#23
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.