Is There a Point in Spending Money on a 12A?
 

Hi all,

I have been doing a bit of research planning on the next steps with my 82 FB.

My car has 66k miles and is basically all original, but I have some longer term goals for it over the next few years.

One item has been the engine/drivetrain. I have considered getting a decent condition 12A to tear apart and rebuild over the winter, but the more research I do I don't see the point in it.

The more obvious direction seems to be rebuilding a 6 port 13B and dropping that in with a new carb setup (weber, etc).


The swap is well documented... GSL-SE oil pan and front cover and modifying the mount... in summary. And most likely direct fire ignition with FC coils...

This way I am not spending $$ on a possible paperwight of a 12A (housing damage etc). Spending $1200 in parts to rebuild a dinosaur of an engine...

13B's can be found easier and most likely in a bit better shape. And if major parts need replacement, that can be organized.

Any feedback on this?

So far the only drawback I have found is driveability/tuning issues with carbs.

Going from a stock 12A to a Weber 13B must be night and day.

Nothing wrong with a 12a at all, in fact you have more options with a 12a over a 6 port because of the standard 4-port setup with large primary ports. at 66k if it's been well maintained the housings are probably still in great shape. I have a 6 port 13b with a weber 50 DCO/SP on it and I'd rather it be a 4 port so I could do a standard bridgeport on it, but that's not going to stop me from doing it anyways.

Don't write off the mighty 12A! A well built, maintained 12a will give you years of reliable performance.

I agree with jibaro12a..
Mighty mighty 12a

I have a well maintained 12a right now and zero problems with the motor.

Rest of the car is another story but my 12a runs better then my 13b did and the 13b was fresh rebuild only 5k miles flooded and leaked oil like no ones business.

But it was a crappy rebuild that got put into it. When i found out an oil pressure plate almost fell off and the motor was barely tourqed together and they had reused 144k mile gaskets and was probably just running way to rich or timed wrong.

Ida know didnt know much back then miss my fc.

66k mile 12A should actually be really nice on the inside...

I just tore down a 120k mile 12A the other day. It was really nice inside. The apex seals were down to 5.9mm - 6.2mm but all were intact. The missing chrome was more or less within spec of 1/8" wide by 2 inches long just at the bottom edge of one housing. The other was even better.

Totally worth spending money on it to get it running again.

If the housings are good, sell it and built a tii streetported block.

I wouldn't go the 6 port route. If you go 13B, use the 12A plates and make it a ported 4 port.
That way you can easily get good 13B housings.

All that said, at 66K unless theres been poor maintenance that motor should be almost new
inside it.

Thanks for all the replies so far.

Certainly makes me feel good about my current/original 12A. I have heard nothing but good things about the 12A!

I am more thinking of starting a winter project, and my parking/storage means I can't work on the car over winter.

So I would be looking at picking up another motor to take apart, learn about, and rebuild.

The way I figure it, I didn't think buying an old 12A was ideal. I could get a 13B easier and then go from there.

I will research more regarding 4 port vs 6 port. I guess some sort of hybrid block would be in order.

i guess my main question would be why would you be rebuilding the engine at 66,000 miles? i didn't see where you mentioned it not running. i get building/refurbishing the car and all, but personally, aside from cleaning it up and replacing some gaskets (maybe fixing some oil leaks) you have close to a brand new engine in a low mileage car. unless the engine is busted (internally broken, leak-of-death, etc.) i wouldn't touch it.

12A or 13B will both get you BIG fun in the car, but at the end of it all, what are you looking for?

And my final advise to you
Use the nikki carb as door or wheel choke
Say no to holley and dellorto.
Buy a weber 48 IDA lol

nope 12a's are junk, especially that one. I guess you'll just have to sell it to me...:nod:

also +1 on the IDA, it'll do it all. (except cold starts :P)

Hey man, don't knock what you don't dig!

Give the niiko to TG instead lol

Plenty of good responses!

Well it seems like I somehow took everybody's advice because just a day or two ago I purchased the following from a local rotary head:

--> 12A Streetport. 5000 km on rebuild using all new parts, hard/soft seals. Done by a well known local rebuilder. Housings were nearly brand new. Complete longblock.. alt, water pump, distributor, sensors etc. MSD Blaster 2 coils.

--> Racing beat wrap around intake manifold.

--> An original RB modified Dellorto 48 DHLA. Rebuilt last year. Looks awesome.

--> 83 FB Tranny, freshly rebuilt.

--> Exeedy stage 1 clutch.

--> A custom exhaust utilizing RB header. Has two resonators and a high flow cat to muffle a bit more.

This entire setup was in the owners FB who pulled it for me to do a 13b REW swap. The engine was running beautifully and got a ride in the car etc before it was pulled for me. It was daily driven.

I will update with info in my forgotten about build thread.

My plan is to keep this engine/carb setup as a spare. I will install the exhaust and tranny most likely when I pull my tranny to replace the clutch.

Based on this I will be in the 12A game certainly for years to come.

that's good that you took everybody's advice I'm looking forward to hearing updates about the build thread

Turbo 12a's are very neat, but I have found the cost's out-way the performance gains, but it all comes down to personal preference like everyone has said. If you like wiring Rb20det long blocks can be found from 1100-1300$..... But I guess I'm partial. I really didn't want to spend close to 1000$ on a gasket/seal kit alone....

BT

And I dont feel like sending a fanboy RB20DET to a shop for machining either lol. $$$

Nice engine, but the prices on them and their parts is stupid because every 16 year old boy with his hat on backwards wants one.

My 71,477-mile 12A is seized, probably carbon locked from so many years of sitting. For the cost of apex seals and a gasket set, I got a running V6 to replace it. Now I'm stuck with a 12A that I don't dare try to disassemble to inspect, and can't sell because nobody else wants it either. May use it as a core charge on the V6 that replaced it. I still have 2 weeks before that expires.
If you ever take it on vacation and anything goes wrong, you're in deep trouble. With a piston engine, there's both hope and help.
I've tried a big block for the nostalgia and the novelty. It was fun, but then all too soon the novelty and nostalgia weren't enough to offset everything wrong with trying to daily an impractical engine. Not saying a rotary can't be practical or reliable, but it must be a serious commitment, and probably needs to be confined to it's best place / application. Plus why can't a 1.1L average better than 25-ish MPG in such a light little car with decent aero?
Not hating, just not seeing it.

Mine does a consistent 24 MPG with a little work... But Its loads more fun to drive and isnt found in everyone elses garage, so I like it a lot.

Don't start a Rotary vs Boinger discussion!

If you ask me, an Rx isn't and Rx without a Rotary.

With that being said, I was never in doubt of my Rotary, just between a 12A and a 13B...

Now I am the new owner of a very sweet 12A streetport setup, and have thus committed myself to rotarys for much more time to come.

My 80 Model 7 got 28mpg from Calgary Alberta Canada to Monroe Louisiana with a edelbrock 500cfm carb perfectly tuned with a turbo!!! the gas mileage did go down to about 23-24 through Kansas @ 100mph across the whole state!! try tuning you carb!!! using an o2 sensor with fuel display it helps tons!! for tuning!!

and when ever you have a great setup a new bigger carb doesn't always work better always keep the old one that gets 28 mpg!!!!!!!!! yep I made that mistake :lol: and gained 0 extra hp by going to a bigger carb tried to run the old carb down went to the dirt tracker I gave it to and he done gave to another who gave to another big lesson learned the hard way!! :nod:

I have already gotten 32 MPG highway with a holley-style carb on an original 12A. Notice I said "consistent" 24 MPG. Implying both city driving, highway, and spirited runs on the same tank.

Methinks the carb is fine.


ALSO, if you are running 465-500 CFM carbies on stockport 12A's you get an easy 24 highway just by running them stoic@55 mph. You can push it past stoic with a 4bbl (NA) and get some extra MPG's...

When i first installed my hogged out nikki it got 30 MPG no problem. I've since tuned it richer for power and it gets 23-24 consistently.

I do all my own welding/ machining and is something I wanted to learn while taking the project on. Drop a stock one in and you almost have double the hp and fuel efficiency for the cost of a 12a gasket kit and a bit of time. Seems like everyone who wants one still has a boner for a shift buzzer.lol only kidding but my fuck are you ever ignorant. It's down to personal preference like I said, didn't feel like each persons preference should have been debateable.

BT

Don't start a debate or I'll have to invite you to race lol. Scratch the fuel efficiency comment. I could watch the needle go down under full throttle in my old 12a but if you guys are saying your getting in the 20 mpgs then heck, your doing quite well.

what ya need is some piston power! :-)

(gluten free)

20 MPG on a modded NA rotary.

I'll take that bet ALL day long and twice on sundays

How is stating a fact being ignorant? Anything nissan that begins with "RBxxxx" is boy racer territory and $$$ for speed parts. I can't tell you how many nerds with Nissan Skylines I talk to on a daily basis that dont know dick about their own car. They just spend 1400 dollars on cams here, 900 on a header there, few thousand for stand-alones, and the obligatory 3k bucks for wheels and low profile tires for that "stance". They just know the engine name, and that it is a wet dream for teenage boys who think Skyline>All

I'd rather not have ANY point of reference with that crowd. Not saying you are one, but you cannot deny the following those cars/engines have.

And I didnt knock the swap, you just called me ignorant because I hit a soft spot with the boy racer comment.

I'd ask you to recant it, but I really dont care. You will spend more money swapping to a different engine entirely and hacking up a perfectly good car than you would rebuilding your rotary. Plus, you would probably like it better than a bland datsun 6 banger IMO.

I do it everyday, so you'd be broke before sunday even comes, lol.

maybe at an optimal rpm on the highway, letting off on the exits etc you might do it. I alot of it has to do with how you drive the car.

hell I can get 4mpg better than my wife driving the same car!

but to realistically say average city/highway and not babying it or dogging it......getting 20mpg . i'd happy lose that bet. even the brand new ones can't say that. they get like 16-17 mpg. why do you think the rotary is dying?

Firstly, I run 4 bbl's that allow me to push my AFR's far beyond what even fuel injection can muster and still run properly on my primaries for cruising, which is most of my driving. The benefit of the 4 bbl is having a second half of the carb jetted for power and the rich fuel mix that rotaries need to make peak power. So, its like having 2 different carbs. One for sipping gas, the other for going like stink. Its surprisingly efficient.

Secondly, were talking about the 12A. They got better MPG's than the most recent renesis back in 1982. And that was while they were choked with 3 cats, and a myriad of emissions equipment.

The 12A is a good, and overlooked engine for daily use and reliable performance. You just cant think you're the stig and floor it everywhere. On my last tank of gas, I cruised at around 90 mph for *hours* and had my foot deep into my secondaries screaming through lanes and even a few times breaking 120 mph on the empty freeway. Still got 17 MPG on that tank. Lol.

If you drive with some sense, and stay within in the speed limit and properly tune your shit 20 mpg average is easy. I have been pushing my own farther and farther on each tank with intelligent jetting choices...

yeah, I know how 4 barrels work. I have never had a 12A, just a few 13B's. That said. my build now has a holley 650. I have not even started the engine yet, so jetting is a little ways off. Can you recommend information or tools I might use to make sure I am getting peak efficiency and the right jets?

i've taken my Rx8 on a couple of longer trips recently, and mileage has been fine, actually. last run was 23.9mpg. mileage also appears to be better at 75mph than 65mph. it is true city mileage is bad, but it is gas MILEAGE, so when it take me 30 minutes to go 2 miles to work, gas mileage is going to be bad in everything, as i'm not going anywhere.

my SA, which was completely stock, got 23mpg round trip on the ~1000mile sevenstock journey, 2 years running.

Oops my bad thought you were talking hwy total ...Hey if you can post the carb type and jetting to help out all us idiots that give perfectly tuned carbs away!!!....Boy that was a very very hard way to learn a lesson...but it was definitely learned!!!:blush:

Your as ugly as your are ignorant lol. I was fully prepared to set "facts" to rest but I'll be the bigger man here and say you are absolutely right 12a>rb20. 100% cheaper 100% more power etc.

Bt

I come to this forum to read about rotaries, not boingers.

Hilariously enough, I didnt claim either of those "facts". But 90% of the time i'd argue getting a 12A running in a car that was designed to have one in the first place is easier than ripping it all out and throwing something else in.

But hey, what do I know? Some guy called me ugly on the internet! As for the bigger man argument, try harder.

I think we all need to stop and calm down.

Why stick with a 12A? You can work out fuel mileage and decent reliable hp. Thats an upside to these little motors.

Rb20 i know nothing of it and i feel like maybe ppl should not talk about pistons is it a good engine sure but not here.

Why should anyone spend money on a 12A well as as far i have seen and experienced alittle more reliable then 13Bs sometimes you can workout quite some power with just the carb and some exhaust mods. Do they have tons of HPs no way but thats the fun of it making slighty faster with what you've got.
Hell do a port job to maximize power if you do it just right you will be smooth going for days if your looking at something like an aggresive bridgeport to a simple street port. Why not spend money on a 12A?

Buy arguing guys forget it wether he would rather have a 12a or a bugatti engine is not up to us but us just being able to suggest why he should spend on one. If there will be arguments its probably better to stop posting in the thread.
I like seeing useful post that i can learn from not people bashing on each others age or intelligence.

So lets all hold hands or something make up like the french do with a kiss on the cheek or something like that.

You could do what i just did. I built a 13b using turbo2 irons (which are strong and 4 port) and s5 n/a rotors. I kept it stockport, however the ports are larger than n/a. I just wanted a strong, reliable, peppy engine. Oh then i powder coated it chrome.


Where people screw up longevity is the pursuit for more and more power. The turbo.

nice engine.

Although I have never done a turbo, even a highly modified 13b can be fickle.

thats why I chose the boinger route. when you want 400hp your pushing your luck from a reliability standpoint

and even pulling 225hp out of an NA 13b is gonna be an engine that likes to scream and does not have much bottom end. i.e. streetability

to each his own. I would rather race a rotary though. Love those high rpms. my last one would shoot flames out the back when running her hard. only know because someone told me one night when they were behind me. very kewl

Wise choice. My buddy is putting a 416 ls stroker in his fd. He got tired of worrying if and when shit was going to hit the fan.