Can someone please provide me with some info on removing all the emissions gear from a 1973 RX-2, USA-spec? It seems to have a thermal reactor (yikes!), air pump, and EGR, plus some whacky second tailpipe and a crazy computer thing in the trunk that has something to do with emissions control.

I can take care of the thermal reactor with a header from racing beat I think and then unbolt and remove the air pump and plug whatever ports it uses. What else do I do? How do I properly remove the electrical parts of the emissions control? Does anyone have a list of what vacuum ports will need to be plugged, etc?

 

basically, you unbolt everything from the intake manifold. you'll be left with some nipples that you can cap, a triangular part that you'll need to fabricate a block off plate for as well as another small oval thing that you'll want to block off as well. replace the TR with a head and remove the entire exhaust system. to replace the electrical parts in the trunk what you should do is convert to a MSD setup. you can use Jacobs or MSD or whatever brand you want, but those things in the trunk just control when the retarded points fire based upon temperature and stuff. a MSD unit will completely replace those boxes. check out my mazda site linked below for some more details about replacing the transmission, pedals, engine and everything else. I may even have some recent picks, I haven't looked at it in a while.

 

thank you for the info, I wish I had found your site somehow earlier, it's very good I will be doing the auto->manual swap and removing all emissions junk soon so this will really help.

I'm currently running an MSD box in my BMW, it's a 6A... which unit do you use on the RX-2? Can you use it with the dual distributors or should I swap to the later single-distributor? I'll go look through your site now.

I was going to change the thermal reactor, etc for a Rcing Beat header but from what they told me their header won't bolt up to the stock exhaust so I would have to fabricate my own system

 

I'm not running anything yet, but what I will be running is just stock iginition for an 84 i.e. using one distributor with 2 ignitors. I've got a universal wiring diagram for wiring up that ignition in any vehicle, so I'm just gonna bypass the 73 system all together. I may convert to a MSD in the future, but placement of the unit is an issue and I've heard opposing comments about their durability/longevity which makes me feel like the stock ignitor system will probably meet my needs.


no, the only thing that will mate up to the stock exhaust system is the TR, so if you want a header, you need to replace pretty much all of it. kiss $700 goodbye. I'd seriously consider replacing the original engine though if you are going to go down that route, because the headers are not interchangeable with a later model 12A and you don't want to waste $150 on headers if your early 12A dies like mine did. It's cheaper in the long run to replace the entire engine with a later 12A, whilst keeping all of your 73 specific parts - oil pan, intake, alternator, etc.

HTH!

Dave

 

accidental double post

 

doh

forgive my ignorance but in that case can I use the TR as just a pass-through manifold (disconnect everything from it and make it sit as an exhaust manifold there so it doesn't actually do what it's supposed to)? At that point I suppose I could junk the air pump and all the stupid themosistors, electronics, valves, vacuum lines, etc too.

I can't afford to replace the entire exhaust and spend $150 on a header at the same time right now so I guess my best bet is to remove as much smog junk so the car runs well while leaving the TR in place until I have the funds to redo all of the exhaust.

removing which parts causes this to happen?

thanks again, by the way for what it's worth the MSD 6A, along with their coil and wires and new regapped plugs, really made a noticeable difference for my BMW inline six and so far I have not had any trouble with it.

 

You'll need to remove the thermal reactor and pull out the funny sleeves. Then reisntall it. It'll act like manifold. If you don't want to bother with removing it, you'll need to keep the airpump hooked up. Otherwise, your apex seal springs will flatten very quickly. Wankleguy knows more about this than me.

You only need to hook the MSD to the Leading dizzy. Use the white wire hooked to the points. Then hook the MSD's output wires (orange and black if memory serves) is parallel to two MSD or other new coils and run them directly to the Leading plugs. Basically, you'll have one naked distributor cap (Leading only; it won't work on Trailing, so leave it alone). You'll have the cool simultanious firing of any 2nd and 3rd gen RX-7 (and any 1st gen or older rotary with an MSD or DLIDFIS). Sound good? I know I like the sound of it. Zoom zoom!

Has anyone ever done this before? I know it'll work in theory, but I'm not sure if anyone has ever actually tried hooking an MSD to a twin dizzy car in real life. Anyone?

 

like the other reply says, you can take it off, remove the reversion sleeves and then put it back on, but you do need to leave the air pump functional so that it continues to cool the outer jacket of the TR. As far as the power being robbed from the engine by the emissions system goes, it isn't the 3 smog valves sitting on the intake that cause the loss - you could really leave all those on there assuming they don't leak vacuum. The real power robbing item is the TR itself since it has the inserts which reverse the flow of the exhaust, and then swirl the gas around and funnel it down the restrictive system which includes a presilencer and muffler. So the real performance gain comes from eliminating the TR and going to a header, not from eliminating the clutter by the carb and intake. But anyway, you can remove those valves if you want, but you'll get a lot more backfires when you do unless you lift off the throttle gently.

what you might try doing is what I've done. I have an 80 engine (which has slightly different exhaust stud locations compared to 73) and an regular exhaust manifold from an 84 (which used 3 cats instead of a TR). what I plan to do is have a short down pipe attached to the 84 manifold, using a flange I cut off the head cat. Then what I'll have done at the exhaust shop is get the 3 bolt triangle shaped TR to pipe exhaust flange cut off and then mate up the original exhaust pipe to my new pipe on the manifold. That way I keep the original system for now, remove the TR, remove the TR flange, and get a straight through exhaust manifold until I can afford a complete system. You'd need to find an early (71-75) 12A exhaust manifold from the UK or Australia and then you'd be in business.

ok, thanks much for the report on your MSD.

Dave

 

ah, understood. However I wonder if I bought the $130 racing beat 12A header for the RX-2 and replaced the TR with it, how far off from the stock exhaust would the header's pipes wind up? If they're close enough to the stock exhaust perhaps an exhaust should can just fabricate an adapter pipe of sorts and then I can use the stock system. However that might be impossible given the angle of the TR manifold compared to how the header seems to look. I wish I had one here lying around so I could line it up and see

how far along are you on your 5-speed installation? are you any further than what's written up on your site?

 

You'll also need to remove the stock air injection nozzles and either weld them shut and re-install them, or get some blocking nozzles from Racing Bleat. Don't waste your time trying to modify the thermal reactor, just get a header and presilencer and weld the presilencer to the stock pipe for the cheapest way to go.
The cheapest header from RB is uncollected and will require some sort of collector, I'd get the version that's already collected for simplicity unless you plan to street-port the motor then you may want to eventually go to a full long-primary setup with dual pipes that collect right before the muffler. Also, that hole in the top of the center housing isn't an EGR valve, I believe it's a temp sensor IIRC. Have fun getting the TR off, I'll give you a tip: use a 9/16" u-jointed six-point socket (a socket with the u-joint built in, not a socket with a u-joint adapter attached). Good luck!

 

hmm, I should go and see if I can afford the RB header with the collector, that is a good point maybe a used one is available somewhere.

In my shop manual for the RX-2 (published 1973) they show a "thermal reactor nut removal tool" which already has me worried (becasically a very weird looking custom wrench).

So what if I buy a RB collected header, a reasonably priced off-the-shelf pre-silencer, and take the mess to the exhaust shop and have them weld up everything header-back to y muffler?

Is the "second exhuast pipe" easily removed?

I'd love to take the TR out because then I could lose the air pump and just about anything else emissions-related on the car in one go.

 

hmm... RB header w/ collector is $148 or so, the RB presilencer they recommend for it (looks like a a nice unit) is $130 or so, and then that can be made to hook up with the back part of my exhaust.

They seem to have a different presilencer for automatics and manuals (at least for rx-7 cars)... I wonder if that would be an issue with my RX-2? I want to do the manual conversion pretty much ASAP anyway. I guess maybe i'll just take it one step at a time (manual first, de-emissions second / as money permits)

 

The little "exhaust" pipe you speak of is actually the outlet from the air pump and can be hacksawed off the muffler without much problem. A regular full-length presilencer should work just fine on an RX2 regardless of the transmission. I'd start looking for a pedal set if you're going to do a tranny swap, they may be somewhat hard to find.

 

the thermal reactor is easily removed if the engine is out of the car, otherwise you'll probably need all manner of u-joint sockets to get the two near the intake manifold off. The lower two should be easy to get to from underneath the car.


on a 73 12A the thing on the top of the center housing is a water temp sensor. for later models that have a block off plate there I think that might be for EGR. My 80 12A has a block off plate that definately has exhaust residue in it, while the 84 junker engine I have dosen't have any sort of plate at all on the top of the center housing.

HTH

 

"All manner of u-joint sockets"?

ONE 9/16" u-jointed socket will do the trick.

 

Or 14mm if you can find one.

 

The reason for using the 9/16" six-point socket is that because 9/16" is slightly larger than 14mm, the socket will go on the nut at a slight angle, which makes it that much easier to access.

 

That's a good idea. I know twin dizzy engines had a closer stud spacing. Really good idea.

 

Thank you.

 

thanks for the additional posts, you guys rock

FYI my RX-2 manual pedal box arrived this weekend (got them on ebay for $100 shipped, ouch).

 

just trying to cover my **** on details I'm not sure about. I've only taken engines apart *out* of the car, so I haven't experienced battling the space between the TR and the frame rail . . .

 

that second post is just what i needed in figuring out my ignition troubles!!! :-D

 

the fan will be in a different spot on the 84 rx7 motor than on the rx2, so you might have to move that eventually. or just go get an electric fan.

im still trying to figure out which is best.

 

crap, now that you mention it perhaps it's also the cause of _my_ ignition troubles

 

make sure you use the later model coils when you make the change over - don't use the 72 coils or whatever you have with ignitors . . .