Could you pass Emissions with a 50 year old car?

Thats a kind of interesting question a buddy of mine asked me today.
He wants to know if you could upgrade a 50 year old car, lets say a 1970 Oldsmobile 442 W30 (thats what he got) for example to pass todays emission inspection.
Without touching the drivetrain (no computers, efi and stuff like that) JUST with a custom Exhaust System (featuring Catalytic Converters of course).

Well i told him i dont know but if you can it most likely:
- gets VERY expensive
- takes dual or quad exhaust & catalytic converters
- makes the car run like crap / very slow (will probably cut hp in half)

but actually i dont know.
what do you guys think?

If I remember trying to pass AZ. Smog with a performance engine...leaned out until it barely ran and some denatured alcohol in the tank. Had to be warm and do the final “tune” just before getting to smog test. Would barely run for the 1/4 mile into the smog station. Thankfully they changed the law to classic car insurance...no smog required.

Unless the laws have changed a car only has to meet emission standards required in the year of manufacture.
I think it could possibly be done with EFI and catalytic converters, and that's a big if.

No.

Its just a hypothetic question.
On some cars you would also have no way around getting hardened valve seats as otherwise the lead in the fuel would ruin the expensive catalytic converters you would have to add. But thats not the same as adding computers/efi and stuff like that and has to be done at some point, when the engine gets rebuild, anyway.

Michael_ said:

Thats a kind of interesting question a buddy of mine asked me today.
He wants to know if you could upgrade a 50 year old car, lets say a 1970 Oldsmobile 442 W30 (thats what he got) for example to pass todays emission inspection.
Without touching the drivetrain (no computers, efi and stuff like that) JUST with a custom Exhaust System (featuring Catalytic Converters of course).

Well i told him i dont know but if you can it most likely:
- gets VERY expensive
- takes dual or quad exhaust & catalytic converters
- makes the car run like crap / very slow (will probably cut hp in half)

but actually i dont know.
what do you guys think?

Click to expand...

There's no real reason to think that adding catalytic converters means the power will go away, modern cars have them too. However, even those require some electronics. The old two way converters won't do much for NOx emissions, the modern three way have been in use for nearly forty years now but usually need an O2 sensor to check for richness, and air injectors to add oxygen when needed. Feedback carbs were part of this solution, fuel injection does away with air injection in most cases.

That 1970 Olds probably has high compression, which increases NOx which is why compression ratios were lowered later on until the three ways were developed.

Todays engine computers have to monitor and vary timing and fuel loads multiple times per second, I doubt that a carbed and distributor timed engine would come close to being as clean.

Jerry Hall said:

Unless the laws have changed a car only has to meet emission standards required in the year of manufacture.
I think it could possibly be done with EFI and catalytic converters, and that's a big if.

Click to expand...

that’s how it was in both Ca. And Az.

1990 fuel inj tow truck put 1979 4 barell in put big cat in ran it till hot full tank hi test 1 qt alco , and it passed better reading than org motor . cat has to be as close as possible to motor , still on road passing , did this in 1995 .

Back in the 80s, I owned a 68 Barracuda with a 318 and 904. Here in CA. you had to have it smogged every other year. Back then, to meet the standards you were required to install a NOx reduction device which included two rubber vacuum plugs to eliminate the vacuum advance, and a sticker which warned you not to drive over 60 mph for extended periods otherwise engine damage could occur.

Additionally, I found that you needed to retard the timing to about 1/2 the normal advance and lean the crap out of it.

So could one pass current standards?Probably not.

P.S. I had the vacuum advance hose in the glove box and was reinstalled when I left the station.

I did emissions repairs in WA State in the 1990’s. 1968 and newer cars had to pass a tailpipe test on a chassis dyno.
Most could pass, some would never pass, some were tricky. The person behind the wheel during the test was very important.

There’s no way it would pass today’s standards. They are too low. Multi port EFI, VVT and computers are so much better than a 455 olds with a quadrajet, even if you install cats.

if you lean out to much you will cause misfire which raises your emisions , if i remember right

Ive never had to do a emisions test on my 70 442 W30 OLDS and our 68 mustang.Ithink up here they only go back 20 or 25 years from current calender year

Even here in Commie CA, there were different standards for different cars. A 1970 car would only be required to pass 1970 specs,
Theoretically, you could do an aftermarket EFI kit and run catalytic converters and drastically reduce the emissions even with higher compression.

I have an attached garage. I've run my old cars for upwards 30-40 seconds, and pulled them out, never tripped my co2 detector in the house

Had a 2015 Gm traverse in the garage. Started it, and pulled it out immediately and closed the garage door. 4 hrs later, the co2 went off @ 80. Took awhile to clear the house. I found that odd

I looked into this a few years back (on Google). I remember reading an article that said it wouldn't work, the temperatures needed for the cats to work were all different, and they would be destroyed in no time.

Nevada requires all cars&trucks newer than 1967 require smog unless you have Classic plates. (Classic plate car has to be at least 25 years old and travels less than 5,000 miles a year) I have done 2 cars, a 80 Volare' performance built 318 and a 79 300 360 both with cats removed and both passed with flying colors.

Photon440 said:

There's no real reason to think that adding catalytic converters means the power will go away, modern cars have them too. However, even those require some electronics. The old two way converters won't do much for NOx emissions, the modern three way have been in use for nearly forty years now but usually need an O2 sensor to check for richness, and air injectors to add oxygen when needed. Feedback carbs were part of this solution, fuel injection does away with air injection in most cases.

Click to expand...

Very true to some extent...
IMO....When in 1975, when the catalytic converter were first introfuced, the origional design was to reduce/eliminate both Hydro Carbon (HC) and Carbon Monoxide (CO) emissions thru thermal oxidation over a platinum coated substrate. Many manufacturers used an engine driven "air pump" to furnish the oxygen needed for the converter to work....at least in theory. I think, in reality, the air furnished by the pump, simply just diluted the HC and CO emissions, allowing the vehicle to achieve emission requirements. The origional GM converters used little pellets in the housing while Ford and Chrysler ised a "honeycomb" or monolithic dedign, superior in all regards, due to the substantially less exhaust back pressure and a better conversion reaction.
When regulations required NOx emissions reductions (thank you California), the 3 way converter was introduced. The converter contained the same platinum catalyst and a palladium catalyst was added. Then the infamous Exhsust Gas Recirculation (EGR) dystem was added for further reduction of NOx. Compression ratios were lowered in an effort to reduce NOx formation by lowering combustion chamber temps and to allow operation on lower octane unleaded pump gas (removal of the tetra ethyl lead fraction which poisions the catalytic converter) rendering it ineffective. Engines were modified to operate on unleaded fuel (hardened exhaust valve seats), open chamber heads to reduce quench areas for HC and CO to "hide.
Can "old cars" pass today's emission requirements? ....not likely....but IF that requirement comes to pass, then it should be limited to the year of the vehicles manufacture. AND to have exemptions for these cars based on, perhaps, annual accrued milage. For example, my RS23V0A******, is in storage for approximately 8 months/yr, emitting ZERO emissions. In my example, the car is driven less than 600 miles per year. With a milage exemption, based on the proportion of total annual emissions, for 1970, would be 4/12 based on months of use OR of total annual milage factor of say, 12, 000/yr would be 600/12,000 x100 for a milage factor. Just my opinion of course.
BOB RENTON

My 95 Dakota always posts high NOx when at full operating temps so always went to the station when as little heat in it as possible. Removing the air filter also lowered it readings. Yeah, most likely needed the EGR system cleaned and did that once and the numbers didn't come down all that much. Glad it doesn't have to go on the rollers anymore and I think most places have got rid of them things when the 95's hit 25 years old. Geez, how many people drive these things still?? 103k miles is all mine has on it so it's not like I'm putting out a ton of pollutants....

I got tagged as a gross polluter in 1995 doing a required annual smog test in California. I was required to go to a state certified only smog shop for a retest and if it failed it could not be registered. The state was trying hard to take these cars from us. My car is a 71 road runner 383ci 4spd with air grabber. I had been running a 509 purple shaft direct connection cam. The car tested way over the limit on hydrocarbons which at the time was 100 ppm. So I changed the cam back to the original 90k mile cam and had it tested at the state certified shop and watched the techs doing their best to make it fail. The day I took it to the shop it hit 100 degrees and the shop was non A.C. and they ran it at idle at least 30 minutes. Fortunately the car passed smog no problem way less than 100 ppm hydrocarbon. The next year the smog laws changed an my car was exempt!

Thanks for your replys.

Well i thought maybe a bunch of computers/electronics and efi simply was the cheapest way for the manufacturers to pass emissions. (in terms of cheaper than bigger cats)
but seems like it is really the only way. at least if you want to run on regular fuel.

Glad we all do not have to pass those standards.