My 85 12a automatic has been suffering from a bum transmission that wont go into overdrive as well as severe dowel pin oil leak of death for some time now and I figured it was time to do something about it. My first plan of action was to replace the 12a with a FCinWV built motor with a holley and long primary exhaust system. If the car was driven by me this would have been fine, but as you all know, my wife drives this one and I found myself needing to go a bit further. I decided fuel injection is the way to go, for both driveability if nothing else...women do not seem to take to pulling the choke, pumping the gas, and feathering the pedal until the engine will idle on its own. They seem to be more of a "turn the key and go" sort of a breed. With all that being said here is my plan:

the car that will be our subject: 85 fb auto...




and my donor car



nothing special...its an 88 gxl that I picked up a couple of weeks ago. 59k 13b and auto transmission. Should fit the bill perfectly

 

Ok so here is what I am laying out for all to comment on...

Engine mounting: I believe I can go with either a gsl se subframe or a racing beat front mount brace like this

Front Engine Mount for 12A to 13B RX-7 Engine Conversion - Racing Beat.

this is probably the route I will go...
so Im gonna need a gsl se front cover. Can I use a 12a front cover since I'm gonna premix...? S4 engines wont go into limp mode with no OMP right?

Tranny mount will need to be fabricated I assume since there is no provision to mount an 88 auto trans in a 85 fb.

Drive shaft...custom of course

Exhaust...will be a header with pipe for actuating 6 ports straight back to a prima flow muffler. O2 sensor installed as well

Cooling System...will be short style radiator with 12a FMOC and racing beat braided lines. FC fan clutch with FB shrouds

Engine Control...will be stock fc computer for now, but am not opposed to going MS in the future as time and funds permit. Will be using the fc fuse panel as well as warning light cluster as well. i will be deleting the emissions as well, so no rats nest and air pump...block off plates installed as necessary.

Fuel Delivery...I was thinking of using a gsl se fuel pump external style, but I am not opposed to going after market with a regulator

Please let me know if I am missing anything...

 

I would also like to add power steering to this car...can I adapt the 12a power steering or is it better to use the fc subframe and adapt the rack and pinion? this will not be a race car, just a cruiser so I am thinking the 12a stuff should work just fine.

 

I don't want to be a downer but, that's going to be a ton of custom work and part finding for the end result being a N/A auto. Since you asked for my opinion, yank the 12a & rebuild it. Then find another fb with a working auto transmission.

If you want to continue your plan, I know for certain you will need a custom drive shaft, SE front cover, SE oil pan & fb oil pick up tube. The fb chassis has a couple holes on each side for transmission mounts, I'm unsure how the auto sub frame bolts on but that should be able to mount it with a little fab work. You might want to research but I recall you need to either modify the 12a fuel supply or use the SE gas tank when going fuel injection. There has been quite a few people who have done fc front sub frame and steering, is possible but requires a lot of new parts and fab. If you were to go this route then you could keep the fc oil pan and front cover.

 

I'd use a tall radiator... bigger engine for one, and you're cooling a transmission as well. <- a bigger transmission.

It won't go limp if you pre-mix.

Good gracious 100 bones for a piece of metal that you already have???????? Drill some holes then use a dremel to clean them up and you're good to go.

 

Thanks notveryhappyjack...I wasn't sure if I could just get away with doing the pump. I guess the hunt for a gslse gas tank begins. As for doing a subframe swap, I feeel its overkill for what the cars purpose is. But it would certaily solve a lot of my other wants and needs for the car. And it would just be a 5speed swap away from being a pretty sweet car. @Qindao...I have seen people do this mod, but I felt uncomfortable with how close the hole ends up being to the end of the bracket

 

yep, 12A front cover is fine.

the 86-88 a/t is really close to the 84-85 at, so you will have to make something, but it won't be too bad

nah, the 84-85 a/t shaft should plug right in


i would put the 12A thermostat cover on the FC water pump, and then the rest of the cooling system is just stock FB

yeah gsl-se fuel pump is probably the simplest way

 

Thanks j9fd3s...good news about the drive shaft. On the fueling side of thing then would I need to use a sturdier connection from hose to hard line since I'm dealing with higher fuel pressures? Quick connects etc???

 

efi hose is all Mazda ever used

 

Ok good. Parts acquisition has begun. Gslsefuel pump ordered from Rock Auto. 12a front covers...I have more than a few of those laying around. Probably do some new mounts as well since I'm in there. I could keep my long radiator and use the FC oil cooler mounted in front, hmmm might even be able to use the FC's oil cooler lines as well. Looks like its time to start pulling stuff apart.

 

The edge with the hole is just as thick as the edge on the bottom and top of the bracket.

I've got almost 5k on mine without a hitch.

 

I looked at your picture again...100 bucks is a hundred bucks

I will give it a shot.

 

I'd personally go withthe RB front mount bar. There is no fiddling around with engine location. It mounts perfectly.

Note the engine will be offset to the driver's side. That's just how Mazda did it, and the RB bar keeps this offset. The engine also sits level and it's so easy to get it in there. In a project as important as this one, I'd spend the 108 or whatever it is.

You'll need to trim the edge of the motor mount as the 13B is 20mm longer and hits the front cover on the edge. Easy to trim. RB doesn't mention this though.

 

I'm very glad I put this out there for comment....the feedback has been very insightful.

So here is the revised plan:

Engine Mounting: 12a front cover with racing beat 13b conversion bracket and gslse oil pan with pick up and a modified tranny cross member and 84-85 12a auto driveshaft.

Cooling System: 84-85 long style radiator with fc fan clutch and original 12a shrouding. FC oil cooler mounted on cross bar in front of radiator...hopefully use original fc oil cooler lines

Exhaust: gonna be a gslse header with street port center section exhaust from racing beat (with pre silencers) into single inlet Prima Flow muffler...single inlet muffler is what is on the the car already. Hopefully the backpressure created by the presilencers will be enough to actuate 5/6 ports

Fuel System: gonaa be aftermarket fuel injection pump from summit with barbed fittings 5/16 from tank and 3/8 to rail...(thanks for the tip Jeff)

Power Steering: will be via a 12a pump and a power steering unit which I still need to acquire.

Engine Management: stock fc computer for now...I don't see the need for anything else at the moment.

The goal of course would be to at least retain the stock fc hp levels if not improve on them a little bit. Driveability is the MOST important feature right now (easy start up and go...etc)

Aestetically, I would like it to look almost factory, but not quite.

Almost forgot...I will not be trying to put a stock fc air box in there. Instead will be using this http://www.ebay.com/itm/86-92-RX7-1-...-/380701129257

 

Well.... you have a very pretty FB to start with; as long as the interior matches that purty paint on the outside.

 

I think the inside is pretty neat....

 

 

That interior is gorgeous work. Sounds like a plan, you may have a problem using the 12A shroud as the engine is a little longer. Worth a try though. Simple is GOOD!

 

The 12A fan shroud fits fine in the red car with a tall radiator, 6 port and RB front mount bar with hockey puck motor mounts. We used an FC fan and waterpump.

Just one correction of something above. The MSD pump inlet (from tank) is 3/8" and outlet (to rails) is 5/16". The other pump is 5/16" at both ends, but you'll want to talk to someone at summit to make sure it has nipples at both ends and not a threaded fitting.

Your tank has a 5/16" send and 1/4" return plate installed on top. You could get a GSL-SE send/return plate if you can find one. It has 1/2" send and 5/16" return. However PercentSevenC has an 83 tank which has hardlines plumbed into the tank (not removeable) in 5/16" swnd and 1/4" return and he has no problems with EFI. We only swapped his stock 1/4" hardline under the car to a 5/16" one from a GSL-SE. Was this necessary? Not sure. I'll try leaving the 1/4" return hardline under the REPU as is and see how it wants to run.

 

Looks like its gonna have to be the msd pump...I just got off the phone with summit and that pump that we were looking at is barbed only on one side. The other side is threaded. The msd pump is indeed barbed on both sides as mentioned.

http://www.summitracing.com/parts/msd-2225/overview/

 

i like the interior, is that a miata radio? it fits so well...

 

Oh cool thanks! Yeah thinking about it, the MSD pump is the better choice whether you get a GSL-SE fuel "plate" or not. Glad I have one!

 

My question too.

I like that head unit. I've gotta do something about my FB's head unit, and that might be an option.


Rest of the interior is very nice too. Sweet ride man. Good luck on the swap.

 

The previous owner put in the radio...I want to say it is out of a millenia s, but I could be wrong. It works very well and looks right at home in the fb console

 

Took a vid of the FC on its final start up before pulling the drivetrain