I have read numerous threads regarding the swap of a 1986 13B n/a stick, into a 1984 GS, but cannot confirm what bracket must be bolted to my 12a front cover. I understand that I can purchase the bracket for $80 or so. Alternatively, can I use my 12a bracket, or a GSL-SE 13b bracket?

Is this bracket what has been referred to as the "cross member" or does "cross member" refer to the metal structure that bolts to the car's frame rails, and that the engine mounts bolt onto?

Thanks for your patience and help.
Bob

 

you also need a 13B oilpan. bu it needs to be form an SE 13B

 

I call it the front cover mount because that's what it is. The crossmember is the thing that sort of holds the front end of the car together lol.

I recently learned that the GSL-SE's crossmember's motormounts are actually 20mm further forward so Mazda could use a stock 12A front cover mount to save money. Racing Beat's is a modified 12A mount. The way I'd make it fit would be to slot the front cover mount by 10mm and also slot the holes in the crossmember where the motor mounts sit another 10mm to let the 13B's extra 20mm fit correctly. I've seen two user-modified front cover mounts and they were both hack jobs.

 

I think you can turn a stock RX4 mount around backwards and then you only need to slot the lower mounts a little bit. I could be wrong about this, though, so check it out before you take this as the gospel truth.

 

Having both the stock 12A mount and the RB mount, the only difference I see is the bending of mount. The two feet of the mount that actually attach to the crossmember on the 12A bend about 110-120* back, so the plate that the front cover attaches to is almost directly over the crossmember bolts. The RB mount on the other hand has a shallower bends - only 80-90*. The net result is that the plate the mounts to the front cover is 20mm further out.

I'm sure that hardly makes any sence......

Anyway, why couldn't you just take the stock 12A mount and bend it slightly to match the RB mount, I bet it would look much less like a hack job if you could do this. The only problem I see is that the mount material is pretty thick, so bending could be pretty hard to do.

 

You need a 12a front cover and a 12a motor mount... might need a 12a oil pan... I had a oil pan off a 76 13b and the damn thing was hitting my steering linkage... so I had to use a 12a oil pan...

 

Dont forget that if you go from 12a to 13b you also need to be able to hook up intake/exhaust mannifolds. I figure when/if I go through with such a swap I'd just have some adapter plates made up so I can use my existing header/intake.

 

You need a 13B GSL-SE oilpan, don't think the 12a one will work (it didn't when I tried to drop my engine in the first time).
Get the RB crossmember too, you'll thank yourself. I made an attempt to use a 12a mount that I had slotted to allow it to sit further forward. It didn't work well because it just isn't designed for that exact thing. I'm convinced that using a modified 12a mount would also lead to much more torque-ing of the engine since it won't be nearly as good of a fit.
Like was said, don't forget about exhaust.
If you're using a 12a front cover, then you'll need to do something about the OMP too. I used a GSL-SE front cover because the 86-88 OMP will bolt up to it, but it will not fit on a 12a cover. Don't know what you'll do if you use the 12a cover, maybe just ditch your whole OMP and run a pre-mix?

Good luck, and search for this. I've had my word in countless posts on this subject over the last 6-12 months. Peace.