Catalytic Converters C-Bodies?

Unix

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Hey,

I have a 71 Newport w/ 383 bb and 2bbl. The exhaust setup is dual stainless steel, stock type, 2.5 diameter. I am seriously considering istalling a catalytic converter on each exhaust. I know the fuselage era c-bodies were pre catatylic, but i am just a little annoyed with the pollution - especially when parking in the underground lot i use, the entire garage reeks with fumes, and when i park too long the fans kick on with the warning that the air is too toxic ;)

Anything i should consider when installing cats on a pre-cat car with a carb? Any worries, suggestions?

I did the same on my 87 Camaro with 305 throttle body injection, installed cats and the fumes were really much "cleaner", and i could stand next to a running car "all day long".

Thinking of something universal like these:
Catalytic Converters at Summit Racing

Thanks for any comments
 
Hey,

I have a 71 Newport w/ 383 bb and 2bbl. The exhaust setup is dual stainless steel, stock type, 2.5 diameter. I am seriously considering istalling a catalytic converter on each exhaust. I know the fuselage era c-bodies were pre catatylic, but i am just a little annoyed with the pollution - especially when parking in the underground lot i use, the entire garage reeks with fumes, and when i park too long the fans kick on with the warning that the air is too toxic ;)

Anything i should consider when installing cats on a pre-cat car with a carb? Any worries, suggestions?

I did the same on my 87 Camaro with 305 throttle body injection, installed cats and the fumes were really much "cleaner", and i could stand next to a running car "all day long".

Thinking of something universal like these:
Catalytic Converters at Summit Racing

Thanks for any comments
Well, answering myself, but it's not a good idea. Off wiki.

Any condition that causes abnormally high levels of unburned hydrocarbons (raw or partially burnt fuel or oils) to reach the converter will tend to significantly elevate its temperature, bringing the risk of a meltdown of the substrate and resultant catalytic deactivation and severe exhaust restriction

Dangers​

Carburetors on pre-1981 vehicles without feedback fuel-air mixture control could easily provide too much fuel to the engine, which could cause the catalytic converter to overheat and potentially ignite flammable materials under the car.[31]
 
Maybe start with an FI conversion.
 
While there have been a great deal of advances in emission controls since 1971 I would think one in good condition should not produce the fumes you're talking about. I'd first look at the tune condition of the ignition and fuel, if all is good there then maybe a carb rebuild would be in order. Lastly, could be wear in the engine itself causing a blow by condition. Note that if there are any bad conditions it could, or would, ruin the converters in short order. Just my thoughts, good luck.
 
Consider that until about 1980, all cat converter vehicles were "analog" emissions controlled. CA cars had the electronic carbs first.

IF the carb is adjusted correctly for a good idle (by the rpm-drop "lean best idle" method) AND the main jetting is more OEM-correct than what some might consider "hot rod correct", you should be able to adjust the idle such that LITTLE smell comes out of the exhaust pipes. Plus that, as mentioned, the ignition timing is good, too. And that the ignition system is working well, too.

Chrysler and others put heat shields between the converters and the underbody, but with some ThermoTec wraps and such, that might be an option. Not to forget that you can fabricate some heat shields, too. Also, by observation on our cars, the 8.2CR motors will put more heat into the exhaust outlet gasses than a very similar 9.2CR motor will. As in comparing the heat on the palm of my hand between oujr '72 Newport 400-2 to our '66 Newport 383-2 cars.

Just because the car seems to run well does not mean that it's doing so in the most efficient manner, by observation.

Certainly, a feedback-loop carb control would keep the A/F closer to 14.2 at idle, but careful carb idle adjustment can do similar, by observation, even on a non-emissions control rated carb. I saw that happen on our '66 Newport 383 2bbl way back in about 1968, but as the idle was just a tad un-smooth, I went back to what I had used before . . . without any additional smells than stock, back then.

Your engine combination? Cam, carb, etc.?

Just some observations and experiences,
CBODY67
 
I have to agree with both above. Cats do not reduce a problem engine. You would be far ahead spending the cat money on a Air/fuel ratio guage.
A rich, sooty exhaust is not going to be fixed by a cat. The catalytic converter with try to keep up when new, but will become overwhelmed and start clogging up/become less effective in fairly short order.
Assuming close to stock engine in good shape. Looking at tune and carburetor function.
Running a car in a garage for anymore than necessary without venting exhaust to outside is how people used to kill themselves. You could probably run a new 4cylinder car in a drafty garage all day and not die they are 2 very different engines.
I believe if you install a air/fuel ratio guage you will see your problem. Then go correct it.
 
How about telling us what been done with/to the carb? Just get a jetting kit and make it leaner, that fixed my noxious fumes problem. But you know what's best so go waste your money and install some cat's on a car that doesn't need them! You have other issues that need to be addressed before you do that! Good Luck
 
A too-rich mixture makes a cat converter get tooo hot, which can cause issues with the floorpan AND the carpets/covering on it. I agree, get the mixture under control FIRST.
 
Well, answering myself, but it's not a good idea. Off wiki.

Any condition that causes abnormally high levels of unburned hydrocarbons (raw or partially burnt fuel or oils) to reach the converter will tend to significantly elevate its temperature, bringing the risk of a meltdown of the substrate and resultant catalytic deactivation and severe exhaust restriction

Dangers​

Carburetors on pre-1981 vehicles without feedback fuel-air mixture control could easily provide too much fuel to the engine, which could cause the catalytic converter to overheat and potentially ignite flammable materials under the car.[31]
High UNIX

so are the spark plug electrodes covered with black soot?

Or is the engine oil turning black quickly after an oil change?

Either of these would indicate a running rich condition that would destroy the new catalytic converters.

It’s not a bad idea to minimize pollution. If neither of these tests work, you can take it to a shop which can place a test unit in the exhaust while the car is running. The tester will tell you if you have too many hydrocarbons in the exhaust, indicating rich condition, i.e. unburnt fuel

Make sure your gas air mixture is correct and you can install catalytic converters all you want. Ben
 
Yeah, I'll start with an AFR test.

The engine is in good order mechanically. Complete rebuild 3k miles ago (everything new).

I recently mounted a new 2bbl original rebuild carb (off rockauto). I still need to change the new electronic distrubitor (proform) to a rebuilt original mopar electronic unit. The plug wires and plugs are new, however they do go black quite fast. I believe the problem is with the mixture of the car, running way to rich under normal load. Under WOT the car accelerates like a bat out of hell - well kind of ;)

I'll go with the AFR testing first and try get this all lined up.
 
Yeah, I'll start with an AFR test.

The engine is in good order mechanically. Complete rebuild 3k miles ago (everything new).

I recently mounted a new 2bbl original rebuild carb (off rockauto). I still need to change the new electronic distrubitor (proform) to a rebuilt original mopar electronic unit. The plug wires and plugs are new, however they do go black quite fast. I believe the problem is with the mixture of the car, running way to rich under normal load. Under WOT the car accelerates like a bat out of hell - well kind of ;)

I'll go with the AFR testing first and try get this all lined up.
I think some adjustments and you will be good
 
Yeah, I'll start with an AFR test.

The engine is in good order mechanically. Complete rebuild 3k miles ago (everything new).

I recently mounted a new 2bbl original rebuild carb (off rockauto). I still need to change the new electronic distrubitor (proform) to a rebuilt original mopar electronic unit. The plug wires and plugs are new, however they do go black quite fast. I believe the problem is with the mixture of the car, running way to rich under normal load. Under WOT the car accelerates like a bat out of hell - well kind of ;)

I'll go with the AFR testing first and try get this all lined up.
Good Onya!
Black spark plug electrodes are a bad sign. OTOH, they point you in the right direction: rich mixture.
 
Hey,

I have a 71 Newport w/ 383 bb and 2bbl. The exhaust setup is dual stainless steel, stock type, 2.5 diameter. I am seriously considering istalling a catalytic converter on each exhaust. I know the fuselage era c-bodies were pre catatylic, but i am just a little annoyed with the pollution - especially when parking in the underground lot i use, the entire garage reeks with fumes, and when i park too long the fans kick on with the warning that the air is too toxic ;)

Anything i should consider when installing cats on a pre-cat car with a carb? Any worries, suggestions?

I did the same on my 87 Camaro with 305 throttle body injection, installed cats and the fumes were really much "cleaner", and i could stand next to a running car "all day long".

Thinking of something universal like these:
Catalytic Converters at Summit Racing

Thanks for any comments
I am not a mechanic but there is more to a cat car than just the converter (all kinds of sensors and stuff your car does not have nor was intended to ever have). I guess your idea is one of the worst ones in the history of automobiles. Get your car tuned up or don't drive it if pollution is a concern for you
 
I suggest an aftermarket EFI. Put one on my 66 Nyer and it cleaned things up immensely. Not zero emissions but very little stink now. I got the Fitech 30002 for less than 900 on sale. Add on the high pressure fuel pump and it's around 1100.00 Cheaper than adding cats. And the performance improved too. Fuel ratio is programmable for different rpm ranges and driving conditions. I don't recommend playing with the settings if you have no idea what you're doing. Do some research first. It does come with a decent tune out of the box and is self learning. Holley and others make them too. It's not the easiest install, a return line needs to be routed back to the gas tank. Only issue is make sure your electrical system is up to snuff. It doesn't like low voltage.
 
another consideration is the reason the manufacturers of new cars are going to roller cams...flat tappet cams dont play well with low ZDDP oil...and the reason they took out the ZDDP is that it kills catalytic converters...also i wouldnt necessarily have too much faith in a Rock Auto rebuilt carb ...especially if it was done by an outfit like Cardone...basically a clean it, throw in a gasket kit and throw it in a box... with all the wrong stuff it came in with still present
 
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