DrAwesom

AAAAAAAlrighty folks! I just grabbed me an FB with I'm pretty sure a 12A powerplant in it. I have some lofty goals and would like to know what yall think and if you have any pointers to help with.

It already has a Holley carb on it, although I've yet to remove it and see which one it is. I've done a little looking around and I read about upgrading the oil system, radiator, and some of the seals. The Lapping process is one that I am curious about. Flaking is another problem I am a little confused about. I'd like more information about those things mostly. Oh, and porting procedures...seems to be a little more to that on these puppies than i expected. Any opionions out there that have any good facts to back them up?

As for turbo prep, I'm planning a twin turbo setup to gimmie a broader powerband and cut down on turbo lag. I want to be able to use the little guy as soon as 1500 RPM's. Any opinions? Facts? Experience?

The other things I'm looking at is fabricating a Ford 9' full posi 4-link Independent Rear Suspention with discs (obviously). Any more opinions? Facts? Experience?

Looking also at fabricating some T-Tops or the removable roof. I think I will be doing T-Tops. the removable roof i think would be affecting the structual integrety too much. T-tops would be easy to re-enforce. Im alreay planning to put a hidden roll cage.

Last thing I wanna know about is body kits. Anyone got any lines on em? Good ones? better ones than others?

And if anyone wants to gimmie some solid refernces to businesses that have parts for good prices and what not, I'd be glad to have it. Thanks!

Aaron Cake

iTrader: (1)

Look on the rotor housings near the oil filler neck. It will tell you at a glance whether it is a 12A or 13B, because the number is stamped on the housings.

Lapping is done during the rebuilding process when the side plates are worn past spec. Plates can be lapped several times to bring them back into spec before they become too thin to use.

Chrome flaking is the process of the chrome coating flaking off of the inner friction surface of the rotor housings. It was a common wear issue until Mazda radically improved the chrome process for the '86 and later engines. Some chrome flaking is acceptable when rebuilding the engine. The factory service manual says about 1/4" on either side, but I'd personally limit that to 1/8" because a set of housings with 1/4" of chrome missing are basically past their service life. One the chrome is flaked off, the housings are junk. There is at this point no rechroming process which has worked. If the chrome damage is minimal, then they housing may be able to be resurfaced.

It sounds like you are wanting to rebuild the engine. These videos should help greatly:


13B engine disassembly:
http://www.youtube.com/watch?v=W1MXfs_Srs4

Engine parts cleaning:
http://www.youtube.com/watch?v=U5A5q61bzRI

Rebuild:
http://www.youtube.com/watch?v=ijJeUk_GqiI

Without knowing the goals for the engine it is hard to suggest what oiling upgrades are appropriate. In most cases, for street driven engines and even those putting out some decent power (300+ HP), the stock oiling system is perfectly fine. Unless your 12A has the beehive oil to water cooler. If that's the case, it should be replaced with the oil to air cooler found in earlier and later RX-7s.

The cooling system is about the same. For street driven cars that are stock or mildly upgraded, then the stock system is sufficient. Turbocharging and making some power will require an upgraded rad and generally an electric fan is used to free up space in that area of the engine bay (gets a little cramped with the turbo stuff).

There are about a billion options for apex seals. Generally stock Mazda seals are the best bet. Atkins also has a line of well proven apex seals.

Porting a rotary is like changing the camshaft on a piston engine. There are and have been volumes written about this. Now, the good thing is that most vendors sell port templates so you can easily get the proper shape on the port, and then just worry about the finesse work of blending into the runners. These range from several stages of "street" ports to radical race-only ports like j-bridges.

If you want to see some porting in action, then here's a video I made of the port job I did for my '76 Cosmo. It's a 6 port engine, which is a bit different from your 4 port 12A, but you get the idea:

http://www.youtube.com/watch?v=y1Gy5sVMK3o

Don't waste your time or money with twin turbo systems. Just trust me.

Now, what are your power goals? What is your use for the car? How much money do you have to spend? These are three fundamental questions that must be answered honestly.

I'm unfamiliar with a "4 link independent rear". Normally one would associate a 4 link with a solid axle, not an independent suspension. Independent would consist of either A arms or trailing arms with a separate diff unit. Maybe you can clarify what you mean with a link? This also ties in with your goals for the car.

You'll need to reinforce the chassis considerably along the frame rails and rocker panels. I'd suggest making some sort of arrangement to tie the roll cage into the front shock towers as well as the rears if you are going to cut out most of the roof. Run reinforcement bars along the stock frame rails and tie the cage into them.

There are about a billion different options from simple flared fenders to full wide body. Here's a few examples from Mariah:
http://www.mariahmotorsports.com/exterior_1stgen.htm

DrAwesom

Is this something a machine shop does? How much does it cost?

Are there any pictures on here showing acceptable vs not acceptable? Should I just take it to a machine shop?

Power goals are going to be between 250RWHP and 400RWHP. I don't want to be crazy, but I want power when I want it. Based on my little bit of research, it seems that these engines are not the best for low end torque and I intend to give 'er some bottom end with the rear end gearing and look into the engine upgrades that will hopefully inprove power there.

Use for the car will be mainly a fun street car to take to shows and show off that can perform at a very amateur level on a road course.

Money is as it comes but I have no set budget. Do what I can, when I can, as I can afford it.

This is what we call round here a brain fart. I wasn't thinking when I posted this section. I want to put a full Independent rear suspension in this beast with the pumpkin of a Ford 9" Full Posi rear end. Used em in racing and loved em to death. I just dont know if this will be possible to do the way I want to do it with an IRS. Just curious if anyone here has taken on any kind of project like this.

I am gonna have my work cut out for me here. This is probably gonna be the trickiest fab job of the whole build. I want this thing to be covered almost completely so you wouldnt know its there.

Kentetsu

Great place for performance parts: www.re-speed.com

Sounds like you've got some big plans. Best of luck.





.

Aaron Cake

iTrader: (1)

Most good machine shops can do this for about $100-$150 per iron. Though it isn't always necessary, or really often necessary. Only if the irons are out of spec do they need to be lapped.

Off hand I don't have any pictures. Chrome flaking is fairly obvious though, you'll know it when you see it. Anything wider than 1/8" kills the housing. Normally it will be on the side where the corner piece of the apex seal would travel. Both the Haynes and the Factory Service Manual contain some detailed inspection instructions.


That is a WIDE range. At 250HP you're looking at T3 based turbos. At 400HP you're looking at T4 based turbos. Also I'd make completely different porting suggestions, and the fuel system is totally different between the two. Don't get scared about the seeming lack of low end. A turbo like the GT35R will be at damn near full boost by 3000 RPM and carry that power to redline.

I was once involved in a project of putting the 2nd gen IRS into a 1st gen. It was just a lot of cutting to make it fit, then a tube frame in the rear to tie everything together. Sadly the project stalled and was never completed. There aren't too many examples of IRS 1st gens.

DrAwesom

Well, thats kinda why I have such a big range. I am basing everything on cost of things i want more like the IRS, T-Tops, and experience of working on a rotary engine.

Well, I might have a lead on a 9" so we shall see what actually becomes of it. Lots of things to look into. Its just gonna take time, money, and a little ingenuity.

I acutally took delivery today and have pics to share, just gotta get em uploaded. come to find out some of the leg work is already done for some serious tuning. Holley carb, no specs on it yet, and a Racing Beat intake, as well an an Efan. I am curious if there is any tranny work too. havent gotten it running yet, needs some carb cleaning from the previous owners foolishness, but I think ill have her running in a matter of days!

DreamInRotary

iTrader: (49)

Hey, also being a MN boy, we gotta treat these cars like motorcycles because there was snow on the ground 6 months of the year last winter. So in my winter downtime I am also looking at doing some similar mods to yours except for the rear end work, I do not feel compelled to do that......yet.. I would love a turbo though, for my 12A, and it will be interesting to see how you fix yours up, good luck!!