Catalytic converter question

[denpo]

I bought my '76 with dual straight pipes, while it's good for the performance, I became the top exhaust fumes polluter of my neighbor (I live more or less in a Downtown area).
Also it looks like the whole smog system is gone.
So I'm considering rolling back the car to some more acceptable pollution level, installing a catalytic converter.

-Can I just install the converter or I need to fit a new smog system to have it working correctly?
-What kind of converter should I use, specific corvette '76 one, or aftermarket converter would to the same job?
-Given I have enough clearance, could I install two converter, one for each pipe in the hope it would eat less bhp away?
-Does installing converters have an impact on the exhaut noise level?

 

[73 Mike]

There is no reason that you couldn't just add a pair of high flow cats to your existing setup. The stock version won't fit as it is a single cat , 2 into 1 into 2 system.

If you get decent cats, you probably won't even notice the difference in performance. I think the effect on sound is somewhat variable.

I don't know what the other smog items are for a 76 so can't comment but I presume that the greatest benefit will be from the cats.

 

[big2bird]

I bought my '76 with dual straight pipes, while it's good for the performance, I became the top exhaust fumes polluter of my neighbor (I live more or less in a Downtown area).
Also it looks like the whole smog system is gone.
So I'm considering rolling back the car to some more acceptable pollution level, installing a catalytic converter.

-Can I just install the converter or I need to fit a new smog system to have it working correctly?
-What kind of converter should I use, specific corvette '76 one, or aftermarket converter would to the same job?
-Given I have enough clearance, could I install two converter, one for each pipe in the hope it would eat less bhp away?
-Does installing converters have an impact on the exhaut noise level?

Contact Richard Waitas, R&D, Magnaflow Corp.

 

[denpo]

Contact Richard Waitas, R&D, Magnaflow Corp.

Thanks Bird,
I asked the magnaflow to forward him the thread URL, we'll see if it get thru.

 

[denpo]

Well, looks like my email didn't get thru, big2bird, do you have the guy's email, if so could you PM it to me?

 

[JeffP1167]

I bought my '76 with dual straight pipes, while it's good for the performance, I became the top exhaust fumes polluter of my neighbor (I live more or less in a Downtown area).
Also it looks like the whole smog system is gone.
So I'm considering rolling back the car to some more acceptable pollution level, installing a catalytic converter.

-Can I just install the converter or I need to fit a new smog system to have it working correctly?
-What kind of converter should I use, specific corvette '76 one, or aftermarket converter would to the same job?
-Given I have enough clearance, could I install two converter, one for each pipe in the hope it would eat less bhp away?
-Does installing converters have an impact on the exhaut noise level?

without some sort of air injection I don't think the cats will work right anyways. I could be wrong though but without the air don't see how they could work properly.

 

[TimAT]

All you get with a cat is a secondary burn of the exhaust- IIRC, it cuts the NOX emissions. If the exhaust stinks there's another problem- possibly a too rich mixture, incorrect ignition timing or something like that. Early versions of the catalytic convertors all smelled like rotten eggs when the NOX was converted to whatever it was.
FWIW: My BB with the sidepipes smells better than the wife's PT Cruiser. And it's not just because I'm using better leaded gas.

 

[denpo]

good infos guys, since the car will rest for a while for the frame swap, this become a secondary problem, I guess I'm due for a good tuning when it's back on the road.

 

[mrvette]

All you get with a cat is a secondary burn of the exhaust- IIRC, it cuts the NOX emissions. If the exhaust stinks there's another problem- possibly a too rich mixture, incorrect ignition timing or something like that. Early versions of the catalytic convertors all smelled like rotten eggs when the NOX was converted to whatever it was.
FWIW: My BB with the sidepipes smells better than the wife's PT Cruiser. And it's not just because I'm using better leaded gas.

:lol::lol::hunter: 50 freeking years, and I STILL believe my sniffer over some obscure theory or other.....

:stirpot:

 

[glen242]

I bought my '76 with dual straight pipes, while it's good for the performance, I became the top exhaust fumes polluter of my neighbor (I live more or less in a Downtown area).
Also it looks like the whole smog system is gone.
So I'm considering rolling back the car to some more acceptable pollution level, installing a catalytic converter.

-Can I just install the converter or I need to fit a new smog system to have it working correctly?
-What kind of converter should I use, specific corvette '76 one, or aftermarket converter would to the same job?
-Given I have enough clearance, could I install two converter, one for each pipe in the hope it would eat less bhp away?
-Does installing converters have an impact on the exhaut noise level?

without some sort of air injection I don't think the cats will work right anyways. I could be wrong though but without the air don't see how they could work properly.

49 state L-48 did not have an air pump as factory equipment. I believe the L-82 did.

 

[big2bird]

Well, looks like my email didn't get thru, big2bird, do you have the guy's email, if so could you PM it to me?

Done..........

 

[big2bird]

I bought my '76 with dual straight pipes, while it's good for the performance, I became the top exhaust fumes polluter of my neighbor (I live more or less in a Downtown area).
Also it looks like the whole smog system is gone.
So I'm considering rolling back the car to some more acceptable pollution level, installing a catalytic converter.

-Can I just install the converter or I need to fit a new smog system to have it working correctly?
-What kind of converter should I use, specific corvette '76 one, or aftermarket converter would to the same job?
-Given I have enough clearance, could I install two converter, one for each pipe in the hope it would eat less bhp away?
-Does installing converters have an impact on the exhaut noise level?

without some sort of air injection I don't think the cats will work right anyways. I could be wrong though but without the air don't see how they could work properly.

The early ones yes, the new ones are so effecient, it is no longer necessary.

 

[73 Mike]

Bird is right regarding the various NO pollutants. These will react on the catalyst without any additional oxygen. Partially burned hydrocarbons will need O2 to react with on the catalyst surface. Same goes for carbon monoxide. If you're running a little rich, that's where the additional air comes in. Again, as Bird said, the modern catalysts are more efficient than the older ones but you still need oxygen to be present for the reaction to work. If you are running more or less at 14.7:1 Air/fuel and are getting incomplete combustion, then the converter should help. If you're running a little rich then the addition of an air pump will help. If you're smelling raw fuel in your exhaust, a tune up will help :lol: