Catalytic converters

[MopaR&D]

Check with your DMV about cat replacements. CO just this year, made a rule that all replacement cats had to be CARB cats vs 50 state cats regardless of what the car came with origionally.

I called the Denver Air Resources Board about that, an engineer explained it's only the sale of 49-state cats that has been made illegal. If you show up to the test station with a federal converter they won't fail you because of it. The guy literally said "You could drive up to Wyoming and buy a 49-state cat, install it in your car, take it in for testing and there would be no issues."

It was enacted mainly to protect drivers who don't know any better and would buy cheap cats that would only last 3-4 years, or get screwed by a shop overcharging them for a cheap generic unit. I'll keep putting cheap federal cats in my cars that need testing lol. I think you might even still be able to order them online depending on the vendor.

And the emissions testing regulations started with 1976 model year because that's the first year cat converters were mandated for all cars in the U.S. Some cars may have gotten them a year or 2 before that. I did once long ago have a slant-6 Duster parts car with a cat but I can't remember if it was a 75 or 76 model year.

EDIT: CO has also recently relaxed emissions testing on 1976-1985ish vehicles, buddy of mine has a 1983 Chevy K20 truck with no catalytic converters AT ALL and he didn't get failed because of it. I've been helping him tune it to pass the sniffer test as he's not familiar with older carb'd engines. Also the CO front range has a bad ground-level ozone problem in summertime that's exacerbated by vehicle emissions.

 

[jos51700]

Say what???? Move to Idaho!

If you like what you have, shut up about it.

 

[Jarlaxle]

I called the Denver Air Resources Board about that, an engineer explained it's only the sale of 49-state cats that has been made illegal. If you show up to the test station with a federal converter they won't fail you because of it. The guy literally said "You could drive up to Wyoming and buy a 49-state cat, install it in your car, take it in for testing and there would be no issues."

It was enacted mainly to protect drivers who don't know any better and would buy cheap cats that would only last 3-4 years, or get screwed by a shop overcharging them for a cheap generic unit. I'll keep putting cheap federal cats in my cars that need testing lol. I think you might even still be able to order them online depending on the vendor.

And the emissions testing regulations started with 1976 model year because that's the first year cat converters were mandated for all cars in the U.S. Some cars may have gotten them a year or 2 before that. I did once long ago have a slant-6 Duster parts car with a cat but I can't remember if it was a 75 or 76 model year.

EDIT: CO has also recently relaxed emissions testing on 1976-1985ish vehicles, buddy of mine has a 1983 Chevy K20 truck with no catalytic converters AT ALL and he didn't get failed because of it. I've been helping him tune it to pass the sniffer test as he's not familiar with older carb'd engines. Also the CO front range has a bad ground-level ozone problem in summertime that's exacerbated by vehicle emissions.

83 K20 probably never had cats. Higher GVWR trucks were sold without cats into the 90s!

 

[Kern Dog]

It may still be illegal to defeat or remove a catalytic converter on a 1975 vehicle if it came with one originally, but if you're not ever required to have a smog test or inspection on that vehicle, I don't know how anyone would find out.

A smog tech told me that owners are supposed to retain all emission equipment that are installed on pollution controlled vehicles, even if they are exempt from testing.
In short, your 1975 car is required by law to have a converter but they don't require inspections to validate compliance.

So make sure you follow the law.

 

[Jarlaxle]

A smog tech told me that owners are supposed to retain all emission equipment that are installed on pollution controlled vehicles, even if they are exempt from testing.
In short, your 1975 car is required by law to have a converter but they don't require inspections to validate compliance.

So make sure you follow the law.

I don't have an issue with running cats...I just don't want to buy a nice 76 Dart and discover I need to drop a bunch of money to register it.

 

[pishta]

We dealt with an EPA audit for a 2 year period while they dissected all of our exhaust products. We paid the nations top emissions lawyers a lot of money to help us during this time. Not to sound like a complete JA but what experience do you have with the EPA with respect to emissions?

Soo, is that CARB statement correct in that the CARB branded cats are the same as the "49" state cats but just with an extended warranty? That's what Walker rep told me. If someone had higher failure rates with the non CRB branded cats, that is suspect.

 

[pishta]

A smog tech told me that owners are supposed to retain all emission equipment that are installed on pollution controlled vehicles, even if they are exempt from testing.
In short, your 1975 car is required by law to have a converter but they don't require inspections to validate compliance.

So make sure you follow the law.

View attachment 1715926358

Gut 'em and make them resonators.

 

[Jarlaxle]

Soo, is that CARB statement correct in that the CARB branded cats are the same as the "49" state cats but just with an extended warranty? That's what Walker rep told me. If someone had higher failure rates with the non CRB branded cats, that is suspect.

Walker might be, not all brands. (Especially generic Chinesium. )

 

[pishta]

Exempt in California means you're not required to have a smog test performed to register your vehicle, even when the vehicle is bought/sold. And if you don't need to smog test for your registration, the only other way you'd need to have a smog test done is if you've been cited for being out of compliance (there are no yearly inspections here). But a 1975 vehicle is exempt from compliance, so, how would you be cited?

So I don't know what the EPA would do to enforce that law, or how someone would ever be in a position that the EPA would find out.

It may still be illegal to defeat or remove a catalytic converter on a 1975 vehicle if it came with one originally, but if you're not ever required to have a smog test or inspection on that vehicle, I don't know how anyone would find out.

I often see CHP trucks at on ramps pointing sensors at a 45 degree at the passing cars on a tripod. I think these are CO sensors that will trip if a nasty car drives by. The on ramps are usually based on a green light for entry so these cars and trucks are on it, producing the most emissions at that time. You can't import out of state convertors to CA, no one will ship them to you. You can ship to your mom in Texas and she can rebox them and send them to you in CA, wouldn't see that is being inspected. Rock auto wont even ship brass pieces if they dont have CA cancer warning stickers on them or are on a CA list. They cancelled a water temp sender on my order becasue it didnt have the CA warning sticker on it.

 

[70dart340]

I'm getting old, but IIRC, Honda was the first production car with cats sold in California. American manufacturers said they wouldn't work. Those were my early wrenching years, but I clearly remember working on exhaust systems back then. If the car was 1975 or newer, muffler shops wouldn't touch your car if you removed your cats for headers and duals. Now we have thieves crawling under our cars at night with a sawzall to cut them off to sell to recyclers. I'm sorry about the rant, I guess I'm getting a bit grumpy as I approach my golden years. My 70 Swinger 340 is getting TTI's, 3" pipes, and chrome tips.

 

[ir3333]

How do you mean?

for clean exhaust?

 

[rumblefish360]

for clean exhaust?

OK, cats on our older cars for cleaner exhaust… gotcha.
I haven’t used one on a upgraded engine with a cam. Just on my ‘79 Magnum with exhaust manifolds on a stock 2bbl. engine with the only mods being a swap to a 4bbl. Carter 625 and a MP ignition box since the Leanburn did its normal thing and failed.

The exhaust was 2-1/4 with an H pipe, then twin cats. Exhaust exited at the bumper. It did very well on the test.

 

[ir3333]

I thought they might make a difference. I used to occasionally leave our cruise nights last just to watch the cars all leave.Problem was you ended up with stinging eyes and sinuses from all the idling from the fumes from all the cars.I'll bet a few well tuned engines burn reasonably clean but it's awfully difficult to clean up the idle on big power builds , or engines with long duration cams.
...wonder how much performance loss there would be with dual cats?

 

[pishta]

I wonder what the efficiency of the cats would be without the added air that the smog pumps or pulse induction provides? Heck, some of the cats had an air nipple built into them to inject combustion supporting o2 into the case. Id say to provide that added o2, run a header evac system.

 

[rumblefish360]

I thought they might make a difference. I used to occasionally leave our cruise nights last just to watch the cars all leave.Problem was you ended up with stinging eyes and sinuses from all the idling from the fumes from all the cars.I'll bet a few well tuned engines burn reasonably clean but it's awfully difficult to clean up the idle on big power builds , or engines with long duration cams.
...wonder how much performance loss there would be with dual cats?

Good question. I have heard and read various power losses with cats added on. The whole thing with this is;
Does the car/computer/state demand a cat for operation?
Do you want to run a cat (or pair) to run and burn cleaner? That notation of burning eyes and noses at cruise night, to me, suggests those cars are not well tuned. I’ve stood behind some seriously lower and fast cars that did t do that to me or others. Granted, huge cams and the such can only get so good, but not burn my eyes out! That’s just stupid.

The LOL part is, try and talk to these fellas and all you get is a FU Buddy or Naaaa, I’m good! I know a guy changing his plugs out every 4/5 gas tanks full but doesn’t want to listen to me. “OK! Have fun changing plugs then!”
The only thing he says in his defense, because he really knows nothing! “According to my race track buddy it runs fine!”

I wonder what the efficiency of the cats would be without the added air that the smog pumps or pulse induction provides? Heck, some of the cats had an air nipple built into them to inject combustion supporting o2 into the case. Id say to provide that added o2, run a header evac system.

Believe it or not, I have actually looked this up before but I have not retained the information since it was just simply on the, interesting to know, the side of things. It is possible to look this up.

 

[MopaR&D]

83 K20 probably never had cats. Higher GVWR trucks were sold without cats into the 90s!

Possibly, he said the first time he took it in they failed him for not having cats but then each time after that they didn't care. It has a mild 350 crate engine (from what it looks like) with long tube headers and true duals, none of which looks factory.

Talking about adding cats to clean up the exhaust on a big-cammed or out-of-tune car... Catalytic converters need to operate within a specific temperature range and also need to have the AFR as close to stoich (14.7:1) as possible or they don't last very long. Too cold and/or too much unburned fuel and the substrate material just gets coated with junk and stops doing its thing after a while. Modern cars vary the AFR between slightly rich and slightly lean as you drive down the road to keep the cat(s) working at peak efficiency and "clean" inside. Air pumps were used up until the late 2000s on some cars depending on how much extra O2 the cats needed based on how the engine would burn the fuel.

Up until it got wrecked I had to get my '93 Jeep Cherokee e-tested every 2 years; running a cheap aftermarket cat I'd typically have to replace it every 3-4 years. I later found out that because the 4.0L was never equipped with EGR, the cat(s) wouldn't last as long as in other engines with EGR because there was a lot more NOx they had to "filter" out. EGR (especially if it's cooled) does wonders to reduce CO and NOx and can also boost fuel economy quite a bit, and like vacuum advance has no effect on performance because it only works under light loads.

 

[rumblefish360]

@MopaR&D
Like that post. That’s really the key for a cat to work and live best and longest. I really took the time to get the carb running it’s best when I had to add the cats to the 360. When I had the exhaust custom bent, they put the cats in there approximate stock location. They did an awesome job keeping them as close to the exhaust manifolds as practical and not near anything to burn up.

 

[Cuda Al]

A smog tech told me that owners are supposed to retain all emission equipment that are installed on pollution controlled vehicles, even if they are exempt from testing.
In short, your 1975 car is required by law to have a converter but they don't require inspections to validate compliance.

So make sure you follow the law.

View attachment 1715926358

Correct, ALL cars in California regardless of year must retain all factory emission equipment. If your classic is spotted blowing out smoke and you get sited you will have to pass an emission test that includes the under hood check.

Whereas this is true I have never heard of it happening.


Alan

 

[rumblefish360]

A seldom exercised threat to keep the would be deplorable gang in line….. LOL

 

[Ccas]

Soo, is that CARB statement correct in that the CARB branded cats are the same as the "49" state cats but just with an extended warranty? That's what Walker rep told me. If someone had higher failure rates with the non CRB branded cats, that is suspect.

As you can see by all the various qualified but confusing comments, this whole issue is a sh$%t show. By EPA guidelines, if we wanted to create a CARB approved converter to sell in California or NY, we'd have to design it to fit in the same way the original did. That means no welding allowed. We'd also have to do testing that proves it emits the same or less emissions as the original one's OEM specs approved by CARB in the first place. Yet I see 'weld in' CARB approved cats being sold. So in theory, yes, the cat could be exactly the same as a 49 state approved cat and clearly not be legally sold in CA and now in NY as well. At the time, we were not asked to provide longevity guarantees for such products.

Btw, not to jack this thread, but these same guidelines issued back in 1974 by CARB extend to all types of emissions devices. Super Chargers, Turbos, cams, air filters, Air intakes, Mass Air Flow Sensors etc. All have to be proven to meet or exceed the original emissions once installed on that particular vehicle. So in theory, if you come out with a Catalytic converter assembly for a 1996 Mustang, (which is appearance wise identical until 2004, you could be required to provide testing on each model year from 1996-2004. That's nine years of testing. I know they were working on a solution for this and we are about 2 years removed now but it just shows you the tremendous hurdles required for a manufacturer to want to introduce any type of performance device to your 1975 (ok 1976 ) vehicle in states adopting CARB standards.

 

[pishta]

Correct, ALL cars in California regardless of year must retain all factory emission equipment. If your classic is spotted blowing out smoke and you get sited you will have to pass an emission test that includes the under hood check.

Whereas this is true I have never heard of it happening.


Alan

Nah, never came across that driving here 35 Years. My 57 got 5mpg with a predator carb on its 351C, the 65 Barracuda 340 I had was never checked. What could they check? There were no emissions crap on those to check. (my 65 S had an air cleaner breather tube and a pcv valve, C.A.P stuff..the 57 came with a road draft tube! My friend had a 74 Toyota Corona. All he had to do was provide a carb preheat hose to the air cleaner. So just a sniffer and visual check as it was still smoggable. Passed 3 years in a row. I'm not sure what the ticket would say on a pre 66 (back then) if it were spewing smoke and I'm not sure what test would clear the fix it ticket, a visual no more smoke from a CHP officer?

 

[Mrmolding]

Hey everyone, I'm mainly an FBBO user, a coworker told me about these that were patented in 2020. I think he did not like the ride in my 70 RR. I just started poking around and found this thread to see if anyone had been brave enough to try them out. Very interesting and there is a demo of an old british car with these Classic Car Converters. Curious mainly but I wanted to pass it along to the thread starter. Who knows if they'd work after a few minutes on the highway.

Classic Car Converters — Redback Catalytic Converters (redbackconverters.com)

 

[72bluNblu]

Hey everyone, I'm mainly an FBBO user, a coworker told me about these that were patented in 2020. I think he did not like the ride in my 70 RR. I just started poking around and found this thread to see if anyone had been brave enough to try them out. Very interesting and there is a demo of an old british car with these Classic Car Converters. Curious mainly but I wanted to pass it along to the thread starter. Who knows if they'd work after a few minutes on the highway.

Classic Car Converters — Redback Catalytic Converters (redbackconverters.com)

Interesting. I have seen some people ask about catalytic converters for getting rid of the “old car smell” that comes from the unburned hydrocarbons etc. you get with the older carbureted engines. Personally I like the smell, but of course it’s carcinogenic too. And people that have a 2-story with a bedroom over garage layout might not appreciate it as much either.

The issue is that on carbureted engines the catalytic converter’s tend to foul pretty quickly, they don’t deal with the extra fuel in the exhaust or lower exhaust temperatures as well. It would obviously be different on a classic that had a modern engine swapped in, although depending on your modifications you could just use the converters that would be right for that engine. And running EFI would also solve that issue, although again that would also open up more converter options too.

 

[pishta]

... EGR (especially if it's cooled) does wonders to reduce CO and NOx and can also boost fuel economy quite a bit, and like vacuum advance has no effect on performance because it only works under light loads.

Been preaching that for years. Its a win/win and if your missing that 4 HP during cruise, when its active, your feeling something else. I can buy a 49 state cat online for my 49 state FED Mazda but I have to send a copy of the registration proving its a 49 state car to get it shipped ot CA. This is from Canada so Maybe they are a little cautious or a little ignorant on CARB restrictions. For me to be able to register a 49 state 1983 model in CA was a minor miracle, I think it had to do with a CA lien sale loophole where the seller does NOT have to smog it prior to transferring title. I don't know how it could have been done without the lien sale situation. (He fixed this car for a visiting WA state resident and she never picked it back up so the mechanic took a lien on it and sold it to me).

 

[Jarlaxle]

Been preaching that for years. Its a win/win and if your missing that 4 HP during cruise, when its active, your feeling something else. I can buy a 49 state cat online for my 49 state FED Mazda but I have to send a copy of the registration proving its a 49 state car to get it shipped ot CA. This is from Canada so Maybe they are a little cautious or a little ignorant on CARB restrictions. For me to be able to register a 49 state 1983 model in CA was a minor miracle, I think it had to do with a CA lien sale loophole where the seller does NOT have to smog it prior to transferring title. I don't know how it could have been done without the lien sale situation. (He fixed this car for a visiting WA state resident and she never picked it back up so the mechanic took a lien on it and sold it to me).

49-state cars and bikes can be tagged in Cali as long as they have more than some number of miles. (I want to say 2500...)