catalytic converters wanted

[Surprise]

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.

[bkahler]

Originally Posted by Surprise

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

[Bruce B]

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?
Bruce

[HowieE]

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.

[Kota]

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.

[perryg114]

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

[Keyair]

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!

[Keyair]

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!

[Surprise]

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.

[Surprise]

[perryg114]

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.

[Keyair]

Read about high CO here...
Using Gas Analyzer Readings

[Surprise]

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!

[perryg114]

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

[dadstoy]

Surprise, I think what you should do is spend about twenty grand and swap in a fuel injected blown hemi and then move out of the state of Arizona, hell my brother lives in Idaho and their they all rip off all the smog equipment on their diesels and they can even carry loaded guns behind their seats there!

Oh come on, I'm just kidding!!!!!

Before you run off and do all the silly stuff that would be an absolute waste of money and time, try to solve that actual problem. High CO numbers are an indication that something is not right and this is not going to be solved by doing the silly fixes.

It sounds like you have already done many of the basics such as a tune up. I have been required to smog my MH each year over the past two. I have had to deal with CO too high at idle.

First, you should answer the question of whether you have the Federal model or the California model. If yours was originally sold in Oregon as was mine, you probably have the Federal model. It's too bad that the vin number doesn't state that. The Federal model only came with the air injection system and PCV valve. if there is no provision for an egr valve on the intake manifold, you most certainly have the Federal model. One way to tell is by the casting number on the drivers side of the Quadra-Jet carburetor, that is if it has the original or the proper replacement. You should see a number that starts with 1708. The sixth number if a 1 or 2 is Federal, if 3 or 4 it is California.

Absolutely don't add cats if it didn't come with them from the factory.

Also, absolutely do not disconnect your vacuum advance for the test! Make sure the mechanical advance and vacuum advance are functioning. Also make sure the vac.um advance is connected to the correct vacuum port. Understand the difference between non-ported and ported vacuum sources. Most distributors are connected to manifold or non-ported vacuum. This means the you have a vacuum at idle and none at full throttle. By all means remove your vacuum advance if you are drag racing your AS and have spent thousands of dollars utilizing and tuning such a system. Just joking geez!

Make sure you have no vacuum leaks and ALL vacuum lines are good and connected according to factory specs.

Do not run old fuel for your test. If that tank has been sitting around for a long time, take a nice long trip and fill up with a good brand of fuel before your test. Test with a fresh oil and filter change. Old oil will contain lots of HCs which can have an affect on the test.

You mentioned a popping in the exhaust under deceleration. If you have an air injection system, which you stated you do, this popping is almost always due to the air injection system not functioning as designed. I won't give you an unsolicited lecture on removing your air injection system...I only have one head and it has already been chopped off! There is a running joke about never buying a vehicle from Oregon because the smog equipment had been removed or disconnected. My parents lived in Oregon and so did DadsToy. My father had disconnected the air injection system by removing the belt and pulley. I spent about $70 for new pump, $10 for a pulley, two months figuring out that the pulley bolts were metric, over $300 on the diverter valve and maybe $60 on two new check valves. The original check valves had rusted out and so hot exhaust flowed the opposite direction which burned out the very expensive diverter valve and the pump itself. The vacuum line to the diverter valve was also disconnected and I almost went crazy trying to find a diagram as to where this vacuum line connected to the carburetor. my shirk says I'm all ok now as long as I stay on my meds.

If I understand correctly and that is only about 50% of the time, the air pump diverter valve will divert the pumps air to the atmosphere during high vacuum such as deceleration. If you are popping at this point, I would say the air injection system is not functioning as required. Make such your exhaust manifolds or headers are tight...air getting in here with out an air injection system is usually the reason for popping as well.

Next you mentioned a rebuilt carb...I'm assuming a Quadra-jet. This would be the next thing to look at. It may be running to rich above idle (your load test). One typical reason here is the float is improperly adjusted.

Anyway, you first need to answer the question about federal or California model. If you can find the casting number on the Q-Jet, I can tell you if it is the correct one for 1984.

[Keyair]

Good solid advice Dean!

[dadstoy]

Originally Posted by Keyair

Good solid advice Dean!

Thanks. I was really hoping that Surprise had high CO at idle...I could tell him exactly what to do.

I love that Surprise's smog check usually indicates not accessible to the visual check...wouldn't that be great here in California. The very first thing they do here is walk inside and open the dog house to peek around! This second time I went to a different shop...recommended by the best MH/truck shop in the world, All Wheel Alignment in Redding! . The shop I went to is Richard's Automotive...great guys as well. He was looking around for a bit and I knew what he was looking for...evap canister. So I asked him what he was looking for. I told him this was the Federal model and he said that's why he can't see it. He started to look for the door sticker to see the GVWR and I told him it was 14500 and to look at the sticker on on ceiling above the the drivers seat. He said good enough for him!

He stated the main issue for CO at idle is that when 454's idle so low, they miss fire. He bumps the idle up to the max...800 something, then runs the engine at a higher rpm for a few minutes and then let's it settle down to idle to clear it out and it then passes the idle CO test. Of course proper tuneup, properly adjusted Q-Jet, good gas, engine warmed up, etc. all help out! I was the happiest person in the world when it passed a month ago!

[dadstoy]

And I wasn't kidding about everyone in Idaho driving diesels and with all the smog equipment removed AND carrying loaded guns behind their seats...you see Idaho just like Arizona are not part of the U.S. ( that's a joke for those of you that don't get it...or is it! Interesting in deed!)

[perryg114]

If you put a diagnostic O2 sensor on it you are not working blind. I would say start with the carb. It could be dirty. The check valves for the accelerator pump could leaking all the time causeing a rich condition. Put a timing light on it and make sure the timing advance is working. It the timing is retarded it will not burn clean. Make sure you don't have any dead cylinders. Are you burning oil? Dadstoy's advice about clean oil and new gas is a good one. A good shop like a hot rod or dyno shop should be able to tune your engine with an O2 sensor.

Perry

[azflycaster]

Originally Posted by Surprise

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!

If you fail the test twice you can qualify for a waver. You can find the details online here:
ADEQ: Air Quality Division: Vehicle Emissions: If You Fail the Test