OCDHerb

I'm preparing to reassemble my SA22 and contemplating what to do with the exhaust. I live in Denver so it must pass what they call a two speed emission test, idle and 2500 RPM. There is no visual inspection.

So far I intend to buy a racing beat muffler but that's as far as I have gotten. I'm staring at this 10 pound rusted hunk o' iron that is the thermo reactor. Has anyone ever replaced it with a modern cat? If so what do you do with the little pipe that comes out of the engine and connects to the TR?

I apologize if this has already been covered but I could not find anything. If it has please point me in the right direction.

Thanks for the input. Herb

Mr_Miles

iTrader: (1)

here in Oregon we have DEQ, and in Cali we had the evil SMOG.( I bought smog exempt vehicles in cali because i was a poor high schooler!)

When i bought my car it had the rats nest removed and it had a brand new exhaust set up, with a cat. It had that little pipe coming off of it and it connected to the air pump. the thermo reactor connected to that downwards pointing pipe on the rear of the engine, right? Mine somehow passed DEQ the way it is, but i don't have to pass it so i removed all that junk.. I have the paperwork from DEQ with the big FAIL stamp before the exhaust work and the pass after it.

My advice would be to just get a nice cat and hook er' up and see how close you get to passing.

mazdaverx713b

iTrader: (91)

for an early SA with a thermal reactor, i would ensure the engine is not running rich, you have a solid working rats nest, leak free exhaust, and working air control valve. the SA is tough to get to pass emissions if any of the original emissions and exhaust equipment has been tampered with.

DivinDriver

iTrader: (15)

Key question from me would be, is the system complete (no removed controls) and are your Thermal Reactor, Air Control Valve, and Air Duct (the first section of plumbing behind the Thermal Reactor) in good functional shape?

If yes, you can get an SA to pass with a careful tune & a few spins of the prayer wheel. But the whole intake and exhaust work as a system on the SA - - even the carb tune is specific, since the mix needs to be (ironically) rich enough to keep the TR hot enough to work. Run it too lean, they test'll out as being too rich because they won't burn off the HCs.

The ACVs fail over time, and the Air Ducts (which are a combination of exhaust pipe and heat exchanger, three separate chambers inside it!) tend to fracture with age & shock damage. Both are tough to find, & expensive or not available new (last Mazda price I saw on a new Air Duct, some years back, was pushing four digits). One I'm using right now is welded up from scrounged parts of a fractured one, with all the careful hackery hidden behind the integral heat shield.

In Cali, we have visual as well as two-speed dyno testing (and separate evap testing, the bastards), so I don't have the option of experimenting with cats and such. But keeping the Beastie road-legal has been an epic adventure.

OCDHerb

[QUOTE=DivinDriver;10657550]Key question from me would be, is the system complete (no removed controls) and are your Thermal Reactor, Air Control Valve, and Air Duct (the first section of plumbing behind the Thermal Reactor) in good functional shape?

Thanks for the info. I need much more.

To answer your Q, The car is bone stock. It was a 78 demo. I bought it from the dealer with 7k miles on the odo and have not made any significant changes. When I parked it in 2002 (rust in the RR 1/4 panel was sucking fumes into the car) it was passing emissions.

I'm not sure which pieces of the exhaust are what. Please describe the ACV and Air Duct.

One of my concerns is that the shield around the TR is rusted through at the edges. Does that matter?

This exhaust system baffles me. Pun intended. There is a small pipe that runs from the engine to the TR. What does it do? There is another smaller tube that runs parallel to the main exhaust all the way to the muffler. What does it do?

The rest of the system looks solid albeit with plenty of surface rust. Should I blast it or will that do more damage than good?

I need a new mufler. Is the Racing Beat product the best for an early RX?

Again, Thanks for the help. With a little luck maybe my little spark yellow car will look and run almost as good as your.

Herb

13x

you say this was a 78 demo, when was it made? Just curious as my is a "78"

many ppl swear by RB there has to be a reason http://www.racingbeat.com/RX7-1975-1...sts/16430.html

As far as passing smog I installed a wideband, welded in the bung and adjust as needed when the time comes

opps excuse the dang fart can in pic, that pos is long gone lol

OCDHerb

I think I just had a realization. What I thought was the TR is actually the air duct thingamabob. How can you tell if that POS is operational. Where is the ACV. Ditto for it. Herb

cshaw07

iTrader: (14)

i thought the thermal reactor was the manifold on the 78, 79, 80's the ACV is the thing on the intake mani under the carb over the exhaust manifold that the air pump hooks to.

DivinDriver

iTrader: (15)

The RB muffler is pretty widely acknowledged as top drawer.

The sheet-metal heat sheild around the TR is helpful in keeping it hot, but it's not crucial; a little rust damage is not important to operation.

These pics will help with some of the component ID:





Here's one of the better diagrams of the system I've ever run across:


It's from a document downloadable from Sgt. Fox's site (several, actually) that's really useful in understanding the SA emissions system; it's titled "1979 RX-7 Product Information" and it was used to introduce Mazda dealers to the new tech in the SA. Absolute gold.

Another is the "1979 RX-7 Service Highlights."

You need these.

trochoid

iTrader: (6)

Check your PMs.