12A "Overbuild" First Timer
03-23-13, 08:51 AM
#1
12A "Overbuild" First Timer
Well let's see this is going to be my first time rebuilding an engine solo... I have a 12A from God knows what year, 
, that I'm tearing apart in hopes of eventually putting it either in my 85 GSL, or if its destroyed a nice table or something lol. I haven't done one of these on my own like I said so I will be putting up lots of pictures of what I got to see if any of you veterans can offer your opinion in terms of whether or not the rotors, housings, and plates are reusable. I will say also that I've been on this forum for a while (about an year) just reading different threads on porting, building for reliability, N/A vs. Turbo, efi vs. Crab, Holley vs. Weber/Dellorto. So I will try my best to ask "educated" questions any help would be greatly appreciated.
-Jose
, that I'm tearing apart in hopes of eventually putting it either in my 85 GSL, or if its destroyed a nice table or something lol. I haven't done one of these on my own like I said so I will be putting up lots of pictures of what I got to see if any of you veterans can offer your opinion in terms of whether or not the rotors, housings, and plates are reusable. I will say also that I've been on this forum for a while (about an year) just reading different threads on porting, building for reliability, N/A vs. Turbo, efi vs. Crab, Holley vs. Weber/Dellorto. So I will try my best to ask "educated" questions any help would be greatly appreciated. -Jose
03-23-13, 08:55 AM
#2
A little back ground of this engine I got this engine from a friend, he literally just gave it to me along with some Rx8 wheels. It used to be in his b2000 pickup before he put in the turbo motor he had been building for years... it started and drove fine until he says it blew a coolant seal it would still turn on but would send coolant flying out of the radiator lol. I've had it for a couple of months and after alot of reading I'm finally going to tear it apart.
03-28-13, 11:29 PM
#6
My Makita and my 1/2" always have my back... Rear side housing off now I could see the lovely water marks, I'm surprised this motor still even ran. Now about that rear rotor on the rear side of it i was able to get all the seals off with ease now on the front the side seals and corner seals did not want to budge... If I'm not able to take those out myself can I pretty much count those rotors as "not usable" or would somebody more experienced and skilled be able to remove these without damaging the rotor?
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03-28-13, 11:58 PM
#10
And one of the big questions, the first 2 pictures are the front housing before being touched, like I said I haven't really cleaned anything it was just tear down, the 3rd and 4th are just having been wiped down with a shop rag and some brake cleaner.... Are these housing still good? I've read on here before when speaking about the housing about the chrome but never seen an actual picture of what they looked bad besides the destroyed seal look that tears them up
03-29-13, 12:16 AM
#11
Front rotor seemed much better got all the seals out easily, wiped it down, and packed it up for clean up later... It took about somewhere between 45 min - an hour to take it apart and wipe down some parts I called this 12A "overbuild" because I have a list of things that I have planned that I've referred to as unnecessary or excessive:
GSLSE oil pump
rear stationary gear w/ 3w Bearing
frnt hardened stationary gear
higher Oil Pressure reg
12A Stud Kit
Balancing rotating assembly
s4 water pump
etc.
The problem is the more I read here the less I know which way I want to go (Porting) originally I wanted to do a half bridge and stay N/A. Than I thought about the type of driving that I actually do and thought well maybe a streetport turbo would be fun also
Also having the same dilemma when it comes to 4 barrel or side/down draft... I'm Puerto Rican so if I ask my peers all I got is one or the other followed by a "cuz it's the best" as an explanation. I've come here to read and see what the points are and I'm still stuck somewhere in the middle.
If there is any light you guys can shed on my confused situation, lol, I'd appreciate it I always take the advice of others who know more than me into consideration. Thanks guys I've learned alot just from reading and searching in this First Gen forum. . . btw my FB is DD
GSLSE oil pump
rear stationary gear w/ 3w Bearing
frnt hardened stationary gear
higher Oil Pressure reg
12A Stud Kit
Balancing rotating assembly
s4 water pump
etc.
The problem is the more I read here the less I know which way I want to go (Porting) originally I wanted to do a half bridge and stay N/A. Than I thought about the type of driving that I actually do and thought well maybe a streetport turbo would be fun also
Also having the same dilemma when it comes to 4 barrel or side/down draft... I'm Puerto Rican so if I ask my peers all I got is one or the other followed by a "cuz it's the best" as an explanation. I've come here to read and see what the points are and I'm still stuck somewhere in the middle.
If there is any light you guys can shed on my confused situation, lol, I'd appreciate it I always take the advice of others who know more than me into consideration. Thanks guys I've learned alot just from reading and searching in this First Gen forum. . . btw my FB is DD
03-29-13, 10:40 AM
#12
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Awesome pictures mate! Im getting my fb in the garage today and will defintiely be checkingback with you frequently. Im probably going to be doing a teardown and rebuild as well. Hope the project goes well and keep up the good work. My car has the rb holley kit on it and I like it a lot, not sure if its the best or not but im not changing it bc the previous owner spent all the money on it aha
03-29-13, 04:53 PM
#13
Awesome pictures mate! Im getting my fb in the garage today and will defintiely be checkingback with you frequently. Im probably going to be doing a teardown and rebuild as well. Hope the project goes well and keep up the good work. My car has the rb holley kit on it and I like it a lot, not sure if its the best or not but im not changing it bc the previous owner spent all the money on it aha
03-29-13, 09:32 PM
#16
Regardless of modifications done to the 12A engine... I'd stick with the nikki. Mazda thought it was the best carb for the job.
Maybe boosted I'd use a four barrel downdrafter.
The FSM pages 1:16 and on goes over how to figure wether engine parts are re-usable or not.
The teeth on that stationary gear look a little on the worn side. But I just read you are replacing them anyways.
As for oil pressure.... Maybe the "raise the oil pressure!!!" ideology that seems to emminate from this forum is rotary specific, but an old man (a mechanic for the army in Korea and decades of service experince) warned me about raising oil pressure beyond what the factory intended. He said that raising the oil pressure too much will etch the bearings.... But with the frequency of rebuilding a rotary will go through I guess a couple of bearings is nothing. Also, maybe bearing metalorgy has improved over the past 20 years.
At any rate. Good luck.
Maybe boosted I'd use a four barrel downdrafter.
The FSM pages 1:16 and on goes over how to figure wether engine parts are re-usable or not.
The teeth on that stationary gear look a little on the worn side. But I just read you are replacing them anyways.
As for oil pressure.... Maybe the "raise the oil pressure!!!" ideology that seems to emminate from this forum is rotary specific, but an old man (a mechanic for the army in Korea and decades of service experince) warned me about raising oil pressure beyond what the factory intended. He said that raising the oil pressure too much will etch the bearings.... But with the frequency of rebuilding a rotary will go through I guess a couple of bearings is nothing. Also, maybe bearing metalorgy has improved over the past 20 years.
At any rate. Good luck.
03-31-13, 07:37 AM
#17
Regardless of modifications done to the 12A engine... I'd stick with the nikki. Mazda thought it was the best carb for the job.
Maybe boosted I'd use a four barrel downdrafter.
The FSM pages 1:16 and on goes over how to figure wether engine parts are re-usable or not.
The teeth on that stationary gear look a little on the worn side. But I just read you are replacing them anyways.
As for oil pressure.... Maybe the "raise the oil pressure!!!" ideology that seems to emminate from this forum is rotary specific, but an old man (a mechanic for the army in Korea and decades of service experince) warned me about raising oil pressure beyond what the factory intended. He said that raising the oil pressure too much will etch the bearings.... But with the frequency of rebuilding a rotary will go through I guess a couple of bearings is nothing. Also, maybe bearing metalorgy has improved over the past 20 years.
At any rate. Good luck.
Maybe boosted I'd use a four barrel downdrafter.
The FSM pages 1:16 and on goes over how to figure wether engine parts are re-usable or not.
The teeth on that stationary gear look a little on the worn side. But I just read you are replacing them anyways.
As for oil pressure.... Maybe the "raise the oil pressure!!!" ideology that seems to emminate from this forum is rotary specific, but an old man (a mechanic for the army in Korea and decades of service experince) warned me about raising oil pressure beyond what the factory intended. He said that raising the oil pressure too much will etch the bearings.... But with the frequency of rebuilding a rotary will go through I guess a couple of bearings is nothing. Also, maybe bearing metalorgy has improved over the past 20 years.
At any rate. Good luck.
Also how can I access those FSM pages? Thanks again for the input
03-31-13, 08:56 AM
#18
Yeah, shutup kid.
You can find the full FSM here - Foxed.ca - Mazda RX-7 Manuals
As for the housings, these 2 pics don't look good... but it's hard to tell from these pictures. I'd clean up the housings, remove any carbon buildup, and take some close up shots of any questionable areas. They should be nice smooth chrome everywhere, but some minor chips out of it won't hurt too much, big areas of missing chrome will kill the compression of the motor and you'll need to find new housings.
https://www.rx7club.com/attachments/...-cam00402-jpeg
https://www.rx7club.com/attachments/...-cam00418-jpeg
As for the housings, these 2 pics don't look good... but it's hard to tell from these pictures. I'd clean up the housings, remove any carbon buildup, and take some close up shots of any questionable areas. They should be nice smooth chrome everywhere, but some minor chips out of it won't hurt too much, big areas of missing chrome will kill the compression of the motor and you'll need to find new housings.
https://www.rx7club.com/attachments/...-cam00402-jpeg
https://www.rx7club.com/attachments/...-cam00418-jpeg
03-31-13, 12:40 PM
#20
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As for oil pressure.... Maybe the "raise the oil pressure!!!" ideology that seems to emminate from this forum is rotary specific, but an old man (a mechanic for the army in Korea and decades of service experince) warned me about raising oil pressure beyond what the factory intended. He said that raising the oil pressure too much will etch the bearings.... But with the frequency of rebuilding a rotary will go through I guess a couple of bearings is nothing. Also, maybe bearing metalorgy has improved over the past 20 years.
they have been scanned and are on the foxed.ca website, and step one in the early book includes bumping the oil pressure... http://foxed.ca/rx7manual/manuals/Rx...%20(70-73).pdf
so basically the FACTORY bumps oil pressure in step with hp, so you should too.
bearing etching isn't a problem with the rotary, although it might be for other engines
04-19-13, 10:03 AM
#22
Ok so I've decide to stick with a street port to use in combo with my gt35r... I got was looking into the carb situation and would it be worth it to buy a Holley, or Weber that isn't racing beat? Meaning would I be spending more money buying the $250.00 carb and doing all the work to get it work for my application than just buying the $638 racing beat Holley? I don't want to be cheap and cut corners with this but at the same time don't want to spend more money than I should. I was considering efi but am looking at the comparison of the 2 as I still have time while I'm getting the engine ported and turbo rebuilt. What do you guys think?
04-19-13, 10:31 AM
#23
Meanwhile got my clutch master and slave + new line made, got my racing beat header, and order my stationary gears. While removing the exhaust manifold the top stud on the rear rotor ripped a piece of thread right out of the housing (2nd picture) lucky me I gotta figure out what to do with the now ordering the rest of the exhaust next week
04-19-13, 11:03 AM
#24
Meanwhile got my clutch master and slave + new line made, got my racing beat header, and order my stationary gears. While removing the exhaust manifold the top stud on the rear rotor ripped a piece of thread right out of the housing (2nd picture) lucky me I gotta figure out what to do with the now ordering the rest of the exhaust next week
04-19-13, 11:19 AM
#25
Why are you removing the studs in the housing? There's no need to remove them unless the exposed threads are toast. Looks like its only a small part of the thread and the housing is still usable. Just chase the thread and use some lock-tight and don't remove it again.