I got the 79-85 12A Rx7 Engine Gasket Kit (N201-89-100B) from Atkins and there is a difference between the exhaust gasket on the engine and the one in the kit. The new gasket covers up two ports.
What do those ports do?
Should I drill out the holes in the new gasket?

 

Only if you still want to use the thermal reactor but you should call Atkins to make sure they didn't give you the wrong set.

 

Looks like an FB gasket...
3743-13-889B is the SA gasket
also, since most available 12a rebuild kits are for the FB 12A, you will want to get the SA gasket for the REAR of the Reactor, where it attaches to the exhaust pipe:
8871-13-981
This does not come with the FB kit...
But like t_g_ sez, this assumes you are using the reactor manifold...

Stu Aull
80GS
AZ

 

I guessing Atkins is not expecting me to have/keep the reactor. The description of the kit says 79-85 rebuild kit. I'll contact them about those gaskets.

​​​​​​if I did not keep the reactor, how do you keep it from backfiring all the time? I don't want that. Do I get an exhaust manifold from an fb?
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N201 is the 81-82 12A kit. the 79-80 kit is an 8871 or 8344 if you're in California.

the 79-80 has a different intake gasket too

 

Yep; Cali 79-80 has five holes total; The two large exhaust ports, the two smaller ports to support the thermal reactor's internal cooling jacket, and one more to support the EGR function in the center iron.

 

Only other option is a header system, Racing Beat's being the best out there. FB manifold will not fit or match up correctly with all the various ports on the SA engine.

Stu Aull
80GS
AZ

 

The FB manifold will fit, although I don't know why you would want to use it unless you could find the system cheap. Racing Beat is a little spendy, but definitely the best and well worth the money. My car has gone from the thermal reactor (on an FB engine so it didn't work anyway), to an FB 'system', and now finally it's fully custom with an RB header and magnaflow straight-through as the midpipe presilencer, tied off with whatever muffler the PO installed in my FB parts car.

Are you trying to keep smog status? The thermal reactor already did a poor job considering it's design premise and likelyhood of collapsing, and if you go with an RB header I'm fairly certain you can't retain FB cats. Might be a good time for a full exhaust upgrade, and the cat is up to you as to smell vs strictly performance vs smog legal - lots of things to consider.

Backfiring shouldn't be a huge issue so long as there aren't any exhaust leaks and the car is tuned/running correctly. Also consider that getting rid of the thermal reactor will mean that the ACV won't work correctly, and the SA's used a different means of controlling backfiring/after burn compared to the FB's.

Is the engine a Cali-spec? That extra port in the center iron reminds me of a later year port-air slot for the ACV.