Gibbs

I recently aquired a 1979 RX-7, and am currently in the process of doing a self restoration. The interior is completly stripped except for the dash and drivers seat. I noticed that after running for awhile, after the car warmed up, that the floor above the catalyic converter was really hot, also the whole center of the floor was hot. It even started to burn bits of insulation that were left behind from the carpet. I would un-bolt the converter to see if it's cloged, but the previous owner welded it on for some reason. Do you think it is cloged, or if it's just running rich. What would you sudgest for both these problems.

markusj08

iTrader: (1)

im gonna go with to much fuel. idk in the 7's but in a piston car thats what mainly causes it.

3rd and final 7

iTrader: (9)

it could be clogged. i would check see if you have your airpump and air control valve if not that could clog it due to lack of O2. the ACV air control valve is located on your intake mani and your airpump is driven by a belt. it could also be from a shitty after market cat that cant stand up to the heat. does your exhust dumby light come on, on the light display?

Tobias

iTrader: (1)

Wait a moment.

I thought RX7s prior to 81 had a Thermal Reactor instead of Catalytics. Those things get NUKE hot, if I remember correctly. I remember reading that even if slightly clogged, they could be seen glowing below the car. Give me a second, im going to try and use the search to post a more informative answer on repair. Because http://www.geocities.com/MotorCity/S.../firstgen.html states that "A pair" of catalytics were added in 81, replacing the reactor.

Perhaps the reason yours is welded, is that its after market. Which would mean it isnt holding up the heat, clogged and dying. Remember that raw fuel is often ejected out the back of the engine, and that back firing is usually the fuel hitting the hot pipes coming out. I'd say its time to replace it. Cut the thing off and get something respectable, if your state requires it

risingsunroof82

iTrader: (3)

I had the same thing happen to me! There was smoke coming from the carpet between the seats. Make sure that your heat shields are still between the exhaust and the car. My dad took the heat shields off and needless to say they are currently back on the car!

Tobias

iTrader: (1)

Here: Some interesting info from Mar3

"The thermal reactor is a heavy cast iron piece with multiple shells surrounding it. Any crack in that casting will be hidden. The SA Nikki carbs are jetted rich so that the thermal reactor can burn any leftover HC's in that hellish environment created on purpose to meet emissions of that time. Problem is that when you have a crack or any kind of leak allowing even the slightest amount of fresh air to be sucked into the thermal reactor, your controlled burn of exhaust gases becomes explosive."

Unless your looking to maintain the integrity of the SA and keep her stock, I would replace the system. Racing beat gets good reviews, and are designed to be able to handle the heat and extra junk that our engines love to produce. Here is a link to their website:

http://www.racingbeat.com/FRrotary.htm

Im neither an export of a pro when it comes to the Rex. I'm a work in progress, so dont jump to buying new stuff on my account! Get a senior forum members opinion, like Troichod, wackyracer , etc ,before making any move on that..

PercentSevenC

^ +1

Get one of Racing Beat's full exhaust systems. Problem solved.

risingsunroof82

iTrader: (3)

Here the problem still, If he doesn't have his heat shields on its still going to get hot!
But, if he does have his heat shields on then certainly, go for the good old racing beat exhaust system!

Kentetsu

The two top reasons for this:

1. Loss of leading ignition, or highly retarded ignition. Check for spark on the leading (lower) plugs, and check your timing. This is my bet...

2. Clogged cat.

defakto

I had something like this on my seven when I got it.

For some reason the jacka...owner before me cut and blocked off one of the air hoses coming off the air pump. This thing would get red hot on idle, hot enough that it caught a towel on the garager floor on fire from teh distance of floor to cat.

I just saw it as a good reason to scrap all that hippy (j/k) emissions crap for a nice RB exhaust system.

Gibbs

Thanks for the insight. Just to let you know the heat shields have always been on. I think I am just going to buy a new exhaust system. My manager at work knows a lot of auto tech people and he is looking around for an exhaust system for me, but I will let him know about the Racing Beat exhaust system. If I were to get a new system would it replace the thermal reactor?

risingsunroof82

iTrader: (3)

It would replace everything. It's a major upgrade. Well worth the money!

90turbo1

If You Have A Infared Temp Gun Then You Can Check It.

90turbo1

take the temp gun when motor is warm and point at inlet, write down temp and then measure outlet, they should be close to the same temp, if inlet is considerably higher then you have a restriction.

if the body of the cat is same temp as inlet and outlet then you have no guts in the cat anymore.

if the cat is glowing red then you have toooooooo........ much fuel..

Kentetsu

I agree that replacing the entire system is a good idea, and you can't go wrong with Racing Beat. However, you should still check into the issues I mentioned above, because if you don't have leading spark, or if your timing is off, then a new exhaust will not fix that. Better to have your car running correctly whether you replace the exhaust or not....

redbstd

My goddamn cat cought my floor on fire aaaaaaaaaaaaaaaarrrrrrgggg!!!! Had to jump out and beat it with my shirt

vipernicus42

iTrader: (4)

Hey Guys,

Going to slightly hijack the thread a bit... but Marc's car is having glowing cats as well.

We can't just replace the system yet because it has to go through provincial "Safety Check". No emissions test, but the stock emissions equipment must be "present and intact".

So I'm thinking the possibilities are :

- Big vacuum leak somewhere causing a really lean mix
- Ignition problems
- Clogged pre-cat (because it's precat #1 that I can see glowing first)


We're going to take a known-good carb and intake, temporarily remove the rat's nest and just run vac advance for the dizzy, cap everything else off, and bypass the ACV to send air directly from the air pump to the cats. The "known good" carb already has a manifold with an ACV block off plate installed.

That should give us a test that eliminates a bunch of problems, then we'll toss a timing light on it, and make sure the ignition's working.

If ignition's fine, carb's good, no vacuum leaks exist and the air pump is plumbed straight to the cats, that only leaves clogged cats right?

Any other suggestions?

Jon

Kentetsu

Jon

Wouldn't it be easier to check the ignition first?

90turbo1

why not actually test the car first??

then replaced as needed.

sounds simple to me