NoPistons -Mazda Rx7 & Rx8 Rotary Forum

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-   -   sa 12a same as fb 12a? (https://www.nopistons.com/1st-generation-specific-16/sa-12a-same-fb-12a-67765/)

sen2two 10-15-2007 06:05 PM

my 1980 sa needs a new motor. i found one from a 83. im only switching over the core. is everything the same? like will the manifold bolt up and all that? like i said i'll be stripping it down to the core. so most things will not matter...

Mark7 10-15-2007 07:23 PM

AFAIK yes. Do you plan on keeping the emissions system?

sen2two 10-17-2007 07:31 PM


Originally Posted by Mark7' post='885525' date='Oct 15 2007, 05:23 PM
AFAIK yes. Do you plan on keeping the emissions system?



i spent the first 2 minutes figuring out what AFAIK means...lol



no emissions. no nothing. just RB manifold and holley 600. not much else...

BeaterRX7 10-17-2007 09:15 PM


Originally Posted by sen2two' post='885689' date='Oct 17 2007, 07:31 PM
i spent the first 2 minutes figuring out what AFAIK means...lol



no emissions. no nothing. just RB manifold and holley 600. not much else...

The '83-85 motors have a different flywheel and front counterweight. If you want to keep your existing clutch you will need to use the earlier motor's flywheel and front counterweight. If you want to use the '83-85 flywheel you'll need the larger later clutch assembly (225mm vs. 215mm IIRC).



The '81-85 motors have the ignitors mounted on the distributor. If I were you I'd keep the remote-ignitor '80 distributor and not worry about converting to an '81-85 distributor.



Make sure your RB manifold covers the EGR port under the center ports. If it doesn't you'll need to fabricate a plate to cover it. Being that it's a RB manifold made for a 12A it should work on all the 12As.



The '83-85 12As use the beehive oil cooler instead of the air-oil cooler mounted under the radiator. Just remove the extra coolant piping and swap over your oil filter pedastal and you should be fine.



That's all I can think of...

sen2two 10-20-2007 08:17 AM

damn...thanks! thats some good stuff to know.



so being that my 1st gen has been most likely motor swapped. and has been rebuilt before it made it into my hands after almost 30 years on this earth. im finding that it has a lot of things that are 83-85 on it. how would i know if i already have a 83-85 12a in there??? because i have a 4-puck unsprung bronze cluth on it now. and would really like to use it without swapping the flywheel and counterweight. measure the flywheel???

j9fd3s 10-20-2007 12:01 PM

pics would be good

sen2two 10-21-2007 08:33 AM

camera is busted.....damn it

bigboi12A 10-21-2007 02:59 PM


Originally Posted by sen2two' post='885904' date='Oct 20 2007, 05:17 AM
damn...thanks! thats some good stuff to know.



so being that my 1st gen has been most likely motor swapped. and has been rebuilt before it made it into my hands after almost 30 years on this earth. im finding that it has a lot of things that are 83-85 on it. how would i know if i already have a 83-85 12a in there??? because i have a 4-puck unsprung bronze cluth on it now. and would really like to use it without swapping the flywheel and counterweight. measure the flywheel???



79-80 rotor housings have a square on the top of the housingin in plain sight. 83-85 housings have an H looking type thing on the top of the housing also in plain sight. As far as the flywheel thing its verry easy to see the differance. 79-80 flywheels are thinner and most important do not have any dowel pins that kinda help hold the pressure plate in place. 83-85 flywheels are thicker and have dowel pins that stick out to holld the pressure plate. One more thing un sprung bronze clutches are violent and prone to chewimg up drive train components rear ends and trannys. Plus the bronze friction material tears the **** out of the flywheel surface. But they make they the driving experiance a **** load of fun. hope this helps!!!

sen2two 10-25-2007 03:10 PM

sooo....it does have the square petruding thing coming from the top of the housings. making it a 1980 core. but the flywheel does have dowel pins coming out out if. sooooo....i guess im lucky and wount have to find any parts. cool....



thanks for the help guys...

bigboi12A 10-25-2007 05:24 PM


Originally Posted by sen2two' post='886300' date='Oct 25 2007, 12:10 PM
sooo....it does have the square petruding thing coming from the top of the housings. making it a 1980 core. but the flywheel does have dowel pins coming out out if. sooooo....i guess im lucky and wount have to find any parts. cool....



thanks for the help guys...

yeah u got 79-80 rotor housings. and a later style rotatig assembly, or at leats fly wheel and counter weight. Word to the wise if your gonna use the flywheel from your present set up be sure to use the front counter weight too or u might get shake and bake!!!!

sen2two 10-28-2007 07:51 PM

ok...so i picked up my 83-85 core today. and it has the thinner flywheel with no dowel pins (79-80) from what you said. so i'll still have to switch over the flywheel. so i shouldnt have to swap the front counter weight right???



oh...and the reason im swapping the core is the front rotor weld "welded" to the damn shaft on the other motor. or at least the bearing was stuck to it beyond the point of getting it off. but the motor ran fine until it started smoking like a building on fire. i found a broken o-ring on the rotor that has to be the cause of the smoke. but i shut if off after about 1 minute of the crazy smoke show...that that couldnt of caused the rotor-shaft porblem. any other ideas??? and could the rotor and shaft be re-usable with a new bearing.

bigboi12A 10-29-2007 06:44 PM


Originally Posted by sen2two' post='886524' date='Oct 28 2007, 04:51 PM
ok...so i picked up my 83-85 core today. and it has the thinner flywheel with no dowel pins (79-80) from what you said. so i'll still have to switch over the flywheel. so i shouldnt have to swap the front counter weight right???



oh...and the reason im swapping the core is the front rotor weld "welded" to the damn shaft on the other motor. or at least the bearing was stuck to it beyond the point of getting it off. but the motor ran fine until it started smoking like a building on fire. i found a broken o-ring on the rotor that has to be the cause of the smoke. but i shut if off after about 1 minute of the crazy smoke show...that that couldnt of caused the rotor-shaft porblem. any other ideas??? and could the rotor and shaft be re-usable with a new bearing.

use the fly-wheel and counter weight off the motor thats in the car now put it on the the motor u just got. Think about the this. based on what I have viewd personally and what I have been taught by my elders is that when a bearing seazes on the e-shaft like that its from lack of oil or lack of oil pressure. If a oil control rig goes bad; dries out or just plain breaks that just lets more oil flow through and yes smoke a hell of alot. Are u sure the last time u ran it even though it smoked you didn't rev the **** out of it for more than a minuet? Thats just my two cent though?

sen2two 10-29-2007 07:34 PM

it didnt rev it at all. i drove it at about 2k for a half mile while smoking. then into my garage. and that was it.


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