I'm thinking on changing engines ,in my 85' GSL, from a 12A to 13B engine out of an 85' GSL-SE. I'm looking for some information on what changes will need to be made to make this engine swap work. I have found a good deal for a 6 port SE 13B, w/transmission, and a racing beat exhaust. I have already upgraded the suspension for this rx7, from the standard suspension, found in a GSL to an SE suspension(LSD,brakes,strut towers,etc). Now I might as well change the engine to a 13b, instead of rebuilding the 12A in my RX7, which has started to lose compression

Rebuild the 4 port and go turbo, thats what I think Im gonna do.

Not to long a go I was considering rebuilding the 12A, with 2mm Apex seals, and adding a turbo. Problem is I haven't had any luck finding a turbo kit.

take both engines apart. use the 13Bs rotors, housings and eccentric with the 12As irons. port, polish if you wish and get a carb set up.

^ yep.

[quote name='DJ Rotor' date='May 12 2005, 11:23 AM']^ yep.


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I second that ^

[quote name='treceb' date='May 12 2005, 09:36 AM']take both engines apart. use the 13Bs rotors, housings and eccentric with the 12As irons. port, polish if you wish and get a carb set up.


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OK, so I use the 13Bs rotors, housings and eccentric with the 12As irons. I need to know what will need to be done so I can install the 13B when its ready to be put back into the car. I have the transmission that was running with the 13B before it was removed, I also have the 13Bs oil pan. Do I have to change the motor mounts or will everything line up if I just interchange the plate from my 12A?

You can buy that overpriced hunk of iron from Mazdatrix or just bend up your own front elephant ear mount.....

Or slot the trans mount 1 inch and use the 12A engine mount. That what I did and it works perfect.



Read carefully... Weight transfer... By doing this you just mover 200lbs 1 inch towards the rear of the car. this helps to move the center of gravity more towards the center of the car.

[quote name='ArmyOfOne' date='May 14 2005, 09:49 AM']Or slot the trans mount 1 inch and use the 12A engine mount. That what I did and it works perfect.



Read carefully... Weight transfer... By doing this you just mover 200lbs 1 inch towards the rear of the car. this helps to move the center of gravity more towards the center of the car.


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Does moving the engine back an inch have any affect on everything else, like the transmission, lining up? What changes will have to be made for the 13b wiring?

A little off topic, but several of you have suggested using the 12a end plates. I have concidered doing this, but what do you use for the intake, if going carb? I will assume S4 intake if staying FI.

[quote name='trochoid' date='May 15 2005, 03:55 AM']A little off topic, but several of you have suggested using the 12a end plates. I have concidered doing this, but what do you use for the intake, if going carb? I will assume S4 intake if staying FI.


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You use a Racing beat holley intake.

[quote name='Black8' date='May 15 2005, 07:15 PM']You use a Racing beat holley intake.


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... and make some good damn power I might add.

why is it better to use the 12a irons? and the intake is the 12a racing beat holley.....if u use the 13B rotors housings etc....won't that change the spacing between the end housings b/c the rotors are wider?

[quote name='laundryhamperman' date='May 16 2005, 12:02 PM']why is it better to use the 12a irons? and the intake is the 12a racing beat holley.....if u use the 13B rotors housings etc....won't that change the spacing between the end housings b/c the rotors are wider?


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12a irons are better because you can port those muthas out. the GSL-SE 6 port irons aren't as port friendly. You have to use a racing beat 13B 4-port intake.



That was my setup in my old FB. I used 12a irons, streetported, S5 rotors, e-shaft, SE housings, a bunch of other things I can't remember. I also used the racing beat intake with a 600cfm holley, with mechanical secondaries.....worked marvelously. Lots of power. it was great.

well im a fan of two barrel carbs so thats what went with.

wait...suggesting to slot the trans mount and move it back an inch to use the 12a engine mounts normally.....doesn't that move the tranny back an inch...back up into the drive shaft...moving into the rear axle...u said it worked perfectly...can you explain how please? i like you idea i just want more info..