MtotheIKEo

I have a 79 with a 13B as pictured in this thread https://www.rx7club.com/1st-generation-specific-1979-1985-18/my-79-just-passed-smog-581798/

Anyways, I was given a header for it from someone I know on another board, and I would like to just build the exhaust the rest of the way back as the one on the car looks to be OEM. I am planning on getting rid of the cat(?), air injection pipes, everything. My questions are:
What is the optimum pipe size for a stockport 13B?
I dont want it to be loud at all, quieter the better actually, but at the same time I would like to keep the cost down so buying a $200 RB presilencer is out of the question. Would adding a bullet muffler or aftermarket cat between the header and muffler quiet it down enough?
Do places like autozone/ pep boys/etc.. sell exhaust gaskets, and are 13B manifold gaskets the same for all generations?


Now about the emissions equipment and rats nest. Id like to remove the rats nest and air pump. I thought I read on here not to remove the rats nest while the air pump is still on, and likewise to not remove the air pump while the thermal reactor is still on, is this true?


My goal with the car is just for it to be a fun little toy with a minimal amount of investment. I only paid 700 for the thing, and have no intentions of putting more than $2k total into it for now, which is why I am not just doing a full RB exhaust. Id like to save some for ignition and intake/carb maybe down the road. Thanks in advance for any help or advice.

bstrange99

I think you're going to have to settle for one or the other if budget is the primary concern. With enough money, you can have a reasonably quiet, pretty free flowing exhaust. But for the most part, especially with a header, the quieter you go, the more restriction you put on the system. That being the case, it may fit your preference better if you stay stock. No point in opening it all up to get the performance, then blocking it off to make it quiet.

MtotheIKEo

I dont mind a little noise, I just dont want the thing to be heard blocks away.

Julian

iTrader: (14)

Read the Racing Beat catalog/techical guide

MtotheIKEo

What about the rats nest /air pump. Can they be removed or are they needed as long as the stock exhaust is still there.

I just really wanna clean up the engine bay as much as possible.

trochoid

iTrader: (6)

You will need to upgrade the exhaust before removing the air pump. The SA thermal reactor/heat exchangers have a bad habit of collapsing and plugging even with the air pump due to age/miles.

As far as a pre-silencer, buy a good one. This is what quiets the exhaust the most. You might look into the Borla XS series, make sure it is stainless seel wool lined. 2- 2-1/4 " piping should suffice for a non-ported 13B.

MtotheIKEo

Thanks a lot. Can I remove the rats nest without removin the air pump?

trochoid

iTrader: (6)

Some, yes, but I'm not that familiar with which parts of the nest control the emmissions, or the air pump. You could prpbably remove all of it and the air pump, but who knows how soon the exhaust mani will collapse and plug.

Since you have a 13B, you may not even have the older style thermal reactor, unless it came off of a REPU. Post pics of the logo on the housings and the exhaust mani.

MtotheIKEo

I hope you can tell whats going on from these, if not I can take pics of whatever you need to see.




And here is a picture of down the carb like you asked for in my first thread.

-=DanK=-

I found this in the first gen FAQ section, as well as alot of other useful mods https://www.rx7club.com/1st-gen-archive-71/fuel-intake-rats-nest-removal-79-rx-7-pictoral-457961/

Good luck

Mazdax605

iTrader: (5)

What I am wondering is what engine are you using?It appears to be a 4 port 13B,but I may be wrong.Also that looks like a factory Nikki carb,so you must be using some sort of older intake manifold,and adapting a nikki on to it,or using an old RX-4/RE/PU carb,so my question is what sort of emmisions stuff is being used here.I would think it would be 12A stuff,but then I think why would anyone go to the trouble of using a 13B in the car,and then putting a bunch of emmisions stuff on it.

-=DanK=-

If it were 12a stuff wouldnt you see those 5 ugly vacuum solonoids by the oil filler tube?

MtotheIKEo

I saw that too, and was planning on following it, but needed to know if it was gonna hurt more than help without removing the air pump/having exhaust done/ etc..

MtotheIKEo

I bought the car like this. It is a CA car which has to pass emissions every 2 years, an old guy owned it before me. This swap was probably done 15 years ago also. It appears to have all the 12a stuff on it i.e. rats nest, air pump, thermal reactor. I wish I knew what the motor was from because it would make it much easier to research stuff and pick out parts.

MtotheIKEo

Can anyone identify it?

trochoid

iTrader: (6)

Sorry, I meant to go check some housing earlier today. Looks like a hybrid engine. You have the later SE housings, (84-85), and probably 12A irons. Carb looks to be pre-RX7, Jeff 20B would know which one probably.

Someone went to a lot of trouble to get it to pass emissions.

You will need a header for a 13B when you get to that point. I can't tell if you have a thermal reactor or the later log style exhaust mani. Does the exhaust system have a 2nd pipe, about and 1-1/2" in diameter that parallels the main exhaust pipe?

MtotheIKEo

Yes it does, branches off near the beginning and goes 3/4 the length of the car. I have a header right now for a 13b that was given to me which is why I would like to build the rest of the exhaust. Im just having trouble finding some sort of presilencer to run midstream between the header and muffler.

MtotheIKEo

On an unrelated note, are the rear suspensions the same for SA's and FB's? There is a LSD disc brake rear end at the local pick n pull but it is on a later car ( 83 I think?)

MtotheIKEo

anyone? :x:

trochoid

iTrader: (6)

The pitch for the brake fittings are different and maybe the diff flange and driveshaft. Grab the driveshaft, just in case. Not sure what you will need to do for the fittings.

MtotheIKEo

Fittings I can figure out, I just thought I had read that suspension mounting points may have been different from SA to FB.