mortiky

I'm currently in the process of rebuilding one of my 12a rotarys, and may need to use parts from one or the other. I was wondering if anyone can tell me what parts are the same and which are different...i.e. housings, rotors, e-shaft etc. I have the original 12a from my '79 SA and also an '83 12a I bought used and blew an apex seal....I swapped it in place of the original engine due to a what i'm guessing is a bad oil cont. ring, it smoked really bad anywhere above 4K RPM. Don't have any experience with rebuilding a rotary, I almost wanted to scrap all my rotary stuff do either a 302 or 350 swap, but decided that if i did it i would regret not at least trying to fix it back up with a 12a.

bumpstart

s1 and s2 rx7 12a are fairly similar, with detail changes in the porting , but use the same rotors and can use the same balance weights
( there is detail differences in the stock OEM flywheel mass,, but not the overall eccentric balance )


s3 12a's ( 83-85 ) have different weight rotors to other 12a's ( there is also a decomp 12at in these years )
and as such must retain the eccentric balance if you wish to use these rotors,, and do not mix match with s1/2 rotors


as for you smoking issue,, oil rings is usually an issue on first start,, and when really bad ,, smoky on engine braking vacuums

if the issue is only when revved hard,, it may be something like a faulty crankcase breathing system allowing sump pressure to escalate and force leak across the oil control cases
-- make sure the PCV system is functional!

PS s3 engine plates usually have the under primary inlet ACV port ( for emmisions and air pump passage )
as such the inlet manifold is made to cover over this port
-- s1 and s2 inlet manifolds do not cover it ,, and result is an exhaust leak under the inlet should you use those manifolds on unmodded s3 primary plate

7aull

iTrader: (2)

79 SA housings, if you plan to use them, must be used as a PAIR and they are NOT interchangeable btw front and back!

unless you have rotary rebuild experience, I would _highly_ recommend the DIY-13B 4-DVD rebuild set sold on:
www.diy-re.co.nz

I bought the set and it has provided and excellent, concise details you MUST know to do the job right (which seems to be pretty straight forward so far - I'm in the middle of a rebuild). Don't let the fact the DVDs are for the 13B, its 99% the same and they do address 12a diffs in the video.

Stu Aull
80GS
Alaska

Jeff20B

iTrader: (13)

I've never bought one, but DIY-13B is a waste of time and money, apparently. https://www.rx7club.com/general-rotary-tech-support-11/best-dvd-13b-rebuild-536184/

7aull

iTrader: (2)

Hey Jeff-
looked at the thread. Thanks. Frustrating because no one sez WHY they don't like the DIY13B DVD set.
It goes into a LOT of detail (as it should with 4 discs!) none of which seems to contradict other rebuild sources. I also have the Atkins DVD which (obnoxious music not withstanding) seems good _as far as it goes_! But it did leave a lot of gaps in detail a newbie like me needed. Details well presented in the DIY set.

I am curious about mazdatrix version tho! Will add to my collection.
Sorry Mortiky - this back and forth may not be helpful to you! For me, with a BIG investment in new housings alone, buying 2 or even 3 sets of DVD sources and plundering/combining the info is just smart $$ spent for my time and money in my rebuild. Besides, whatever you buy, you can always get some return $$ reselling them after. Can't have too much info on a rebuild project IMHO.

Best of luck
regards
Stu Aull
80GS
Alaska

Jeff20B

iTrader: (13)

Go to page 2, scroll to post #31, #32 and #33 for three individual opinions why they don't like DIY-RE.

rx71king

iTrader: (6)

i have a old rebuilding video. send me $5 and i will mail u a copy. po box 640012 oakland gardens n.y. 11364