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Old 10-15-2012, 10:28 PM   #1
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1984 31' Airstream310
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catalytic converters wanted

Anybody recommend where to get a couple good catalytic converters for the 454 dual exhaust? Previous owner said they were never installed and now I can't pass the CO portion of the test here in AZ. Got a price for $165 a piece from the neighborhood muffler shop, but I'm concerned that they will not last very long or rob horsepower.
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Old 10-15-2012, 11:18 PM   #2
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Quote:
Originally Posted by Surprise View Post
Anybody recommend where to get a couple good catalytic converters for the 454 dual exhaust? Previous owner said they were never installed and now I can't pass the CO portion of the test here in AZ. Got a price for $165 a piece from the neighborhood muffler shop, but I'm concerned that they will not last very long or rob horsepower.
Interesting. Our 84 310 has the banks power pack installed and passed all emissions tests in California. I didn't think the big rigs were required to have catalytic converters in 1984.

I would suggest looking for a different source for your CO problem. Putting cats on might just be masking a different or larger problem.

Good luck.

Brad
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Old 10-16-2012, 01:24 AM   #3
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I am curious, how does Arizona test emissions on that rig? Is it just a two speed idle test or are they running it on a dyno? Do you have the target numbers and how badly did you do in the test?
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Old 10-16-2012, 08:11 AM   #4
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I find it very strange that a truck would even be tested for emissions let along one of that year.

I would contact GM to see it the truck was so equipped at time of manufacture.
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Old 10-16-2012, 08:28 AM   #5
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First of all, this is just my opinion as a mechanic and engineer. Howerer, I am typing this from the lobby of a Holiday Inn Express.

1984 was a bad period for "smog" equipment. Nitrous oxides, a byproduct of high combustion temperatures, seemed to be the major concern in an era of realatively cheap gas. The solution to lowering NOx was to lower combustion temperatures by lowering compression ratios and running a richer mixture. The excess CO and unburned hydrocarbons that resulted were treated by injecting air (Air Pumps) into the exhaust path and oxidizing them in simple catalylit converters. They produced a lot of heat and had to be shielded from both the chassis and the grass on the ground. The system robbed power and economy. Thus, the reason it bacame popular to remove the equipment and lean out the mixture which lead to all the laws and inspections.

This lead to the developement electorincally controlled fuel injection and emmisions control system. We now rely on computers, oxygen sensors, etc... to optimize the operation of the engine. In most modern applications air pumps are no longer necessary.

Modern 3 way catalytic converters break nitrojen compounds into nitrogen and water vapor. CO and hydrocarbons are converted into CO2 and water vapor.

Putting a 3 way converter on your carburated engine would probably cause it to over heat and burn out or possibly burn up your AS. If you do install one, make sure it's the correct type, size, and is appropriatly shielded or you may be creating a whole bunch of unintended problems.
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Old 10-16-2012, 02:50 PM   #6
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Summit Racing has them. Consider getting rid of the carb and converting to throttle body fuel injection and then you will have a much better, cleaner, more powerful system. I would think that with a vehicle that old and that size that the restrictions were much less tight than a car of the same vintage. Are you sure they are putting you in the correct classification?

Perry
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Old 10-16-2012, 03:07 PM   #7
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1984 34.5' Airstream 345
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Surprise...
I have a federal smog 1984 Airstream 345....
It has had some of its smog equipment removed...
I am in California, which I think is the toughest Smog in the country...
I have done my research, and have solid evidence.
Here is what I know.

In 1984 the Chevy Chassis Medium/Heavy Duty Class A Motorhome with FEDERAL(non California) Smog equipment had:
No Computer, 4 Barrel Carb, timing was 4deg at 700rpm, PCV Valve, AIS system with Single Smog Pump with Air Injection into the exhaust Manifolds, NO EGR(except CA), No Evap Canister(Except CA), and SPK(spark control).

There is no Catalytic converter or O2 sensor.

I got my information here:






It is my understanding, that there is a Federal mandate, that you cannot remove smog equipment even if you have no smog regulations where you live... but equally you are not required to add or update smog equipment either.

The rules here in CA are that ALL of the originally fitted emissions equipment must be fitted and functional... They do a visual inspection and refer to the Book that I pictured above.
Then they do the emissions test...

Please feel free to ask questions!
Post a pic or the numbers of your smog test failure, and the numbers your MH gave... it will help us figure out maybe what is wrong.
I would LOVE to see some pictures of your engine as it may help me make sure I have everything and help us to you too!
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Old 10-16-2012, 03:13 PM   #8
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You should have a sticker on the Airfilter housing that looks like this..
I got this pic from Airforums Member Kmpro, who had a 1984 Federal 310..
This is a diagram of the emissions hoses and equipment, and this is what I am using to reconstruct my smog equipment!


I am having to go step by step...
My Carb is wrong(should be a Quadrajet), my Airfilter was wrong, my smog pump was missing, the Air injection pipes in the headers are plugged, and I have much of the piping missing or disconnected...
I now think I have all of the jigsaw pieces.... just have to put them in place!

Perry... adding FI is a great idea, but in some states, like here in CA, you cannot do it without huge issues with smog.
Not to mension cost!
Sunrise has to smog the MH in Az.... so I bet any changes made have to adhere to the rules there.
In CA, any changes have to be CARB approved, and none of the aftermarket stuff is... or swap in a FI system or motor from a later model...
A good cost effective example of such a swap would be to put a TBI(Throttle Body Injection) system from a late 80's 454 truck like a suburban. Here in CA, you have to get that swap inspected and approved by a Smog Referee... which is $$ and also means that the MH would need to pass the smog test of the doner vehicle's year... which might be a bigger issue than fixing the original issue!
I have the complete motor and TBI system from a 1990 Suburban in my storage...and an shying away from doing the fuel system swap because I know it could bring more cost and issues than it cures!
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Old 10-16-2012, 07:40 PM   #9
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Attached is the failed emissions report. I tuned it almost exactly as the air cleaner specs say to. Timing-4 btdc, idle 700 rpm, air mixture screws approx 3 turns out, vacuum advance disconnected during test as well (I've found this helps under the loaded test in other normally aspirated engines). Maybe this vehicle didn't require Cats, it was purchased in OR. The air pump it's installed and everything seems to be functioning properly. New rebuild on the carb, new plugs, wires, pcv valve. I have noticed that I get a lot of popping from the exhaust when letting go of throttle or descending down big hills. Is assumed this was because the lack of Cats to burn off un-burnt fuel in the exhaust.
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Old 10-16-2012, 07:42 PM   #10
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Old 10-16-2012, 07:59 PM   #11
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The popping is usually due to a lean condition. It looks like you are running rich under load. Look for intake restrictions or someone put a bigger carb on it. Why do they care what is under the hood as long as it meets the emission specs? If someone decides to upgrade the emission system and make it better than it was, why should they complain? You can get data logger system that uses an O2 sensor to tune your carb properly. Putting CATS on it may help you in some areas and hurt you in others. In my opinion, you should not put CATS on an engine unless it has closed loop control to the O2 sensor. This is how all modern engines work. Dyno operators use something like this to tune race engines for optimum Horse Power without melting something. Carburetors suck because they cannot compensate for air temperature, Altitude, and Fuel Quality. Computer systems constantly monitor the fuel air ratio via the O2 sensor. The amount of fuel is constantly varied based on sensor inputs like air flow (CFM), air temperature, and fuel air ratio.

http://www.innovatemotorsports.com/

Perry

P.S. Don't forget these folks work for you. You pay their taxes. Make them accountable for their actions and make the justify all their BS. If they can't explain something move up the food chain. I don't suffer fools well and niether should you. They should be able to tell you why a reading is the way it is.
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Old 10-16-2012, 08:07 PM   #12
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Read about high CO here...
Using Gas Analyzer Readings
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Old 10-16-2012, 08:46 PM   #13
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1984 31' Airstream310
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The two times I've taken the MH through emissions, they never even ask to open the dog house. They just mark down inaccessible. I'd rather not add Cats and I'd like to rip the air pump out completely. The engine is a rebuild from GM but all accessaries are original. I have read that a lean condition can cause the popping but at the same time high CO levals seem to derive from overly rich conditions.....Go figure!
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Old 10-16-2012, 08:50 PM   #14
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So if you upgraded to a modern throttle body injection they would not know. I would start with an O2 sensor to see what the mixture is.

Perry
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