i was wondering if anyone knows if a crossmember from a normal fb with a 12a will fit a n/a 13b? like would it be a straight bolt onto the motor or some modification has to be done? this is goin in my rotary ae86 btw

it is not the 12A is a shorter motor than the 13B. Also the 12A mounts to the crossmember using the front cover. The FC 13B mounts to the motor using motor mounts further back. The FB 13B mounts just like the 12A only uses a differents crossmember.

If you look at my build up pics and compare to your car you should be able to see what I mean.

http://www.coloradomazdaclub.com/forums/showthread.php?t=3344

I did some research on this a while back...if I remember right you can't bolt up a 13B from an FC, but the differences are minimal. Like Chris said, FB motors bolt up using the front cover. So, you have to use a 12A front cover. You also have to use the oil pan from a GSL-SE FB, the late model ones that came with a 13B. It won't fit over the FB crossmember. What are you planning on running for engine management?

From what I understand you want to put a 12A into an FC, is that right?

It sounds like he is trying to put a 13B from an FC into an AE86 using a 12A FB crossmember...I think?

the position of engine will move back in the original chassis. If not in the original chassis, then it matters not. Plus you can just bend and slot the cross piece.

Ranger wrote:It sounds like he is trying to put a 13B from an FC into an AE86 using a 12A FB crossmember...I think?

yea trying to achieve something like this but kinda gave up on making mounts too much work, so i figured an fb crossmember would work

Ok I understand what you are looking at. What you will need is a 12A or FB 13B front cover and a FB 13B oil pan. You can get a new pan at mazdatrix if you can't find used. I have a 12A front cover if you need one, I'd sell it to you real cheap.

That is probably the best way for you to go, much easier then doing the mounts for the FC motor.

yea i've tried making mounts and it jus wasn't working out too well, so this is one of the simplest things i can do for now. wouldn't the 13b front cover off an fb be a better solution rather than a 12a? cuz i noticed that the 12a front has the two distributor holes and the 13b from the fb doesn't. do i jus simply block those off or some mods has to be done? im keeping it FI btw

Ranger wrote:I did some research on this a while back...if I remember right you can't bolt up a 13B from an FC, but the differences are minimal. Like Chris said, FB motors bolt up using the front cover. So, you have to use a 12A front cover. You also have to use the oil pan from a GSL-SE FB, the late model ones that came with a 13B. It won't fit over the FB crossmember. What are you planning on running for engine management?

thinking of using an stock ecu from an fc if not megasquirt

THe 12A out of the rx-7 only has one distributer and is actually the same distributer as the FB 13B. The 12A out of the RX-2 has 2 distributers. The front covers out of the FB's are basically the same.

ahh i see, then ill probably get that front cover from you.

if you have questions on the megasquirt, let me know

I did some research on the and the 12A front cover is the same excepted the OMP. The FB 13B uses the same OMP as the FC motors but the 12A is different. Other then that they are the same. If the still want the 12A front cover, I'll sell it to you for $30 if that works.

It might be best for you to loose the OMP and do premix then you could do synthetic if you want. I didn't do this on my car because it can be a pita to mix oil at all gas fillups.

http://www.rx7club.com/showthread.php?t=797259&highlight=front+cover+12a+13b

i think the MOP itself is the difference though ( 2 outs (12A) instead of 4 (13B)). i would like to see if the S4 mech MOP would attach to the 12A cover.