Hello everyone,

I've brought my 1973 Camaro and 1973 Firebird up here to the Denver-metro area after living in New Mexico for many years. Down in New Mexico, you didn't even have to show them the car, they would just give you a plate for it. Up here, it seems as though there is a big deal with emissions and so on and so forth.

Any recommendations? I think it unlikely that my camaro can pass emissions-- I have a little bit of hope for the vortec-head Firebird but not much. Anybody else out there with a "modified" street car around this age? What did you do to get around the emissions test?

thanks for your help! I really appreciate it.

-Matt

you might be OK, what exactly does the state of Colorado expect you to do to get it through emissions ?

A few places around denver test 81 and older,not many a them left. And then you have the state emissions test places. Once you get the car passed, alot of people put collector plates on their cars. Has to be 25 years old for collector plates.

Based on a little research, here's what I've sort of figured out:

Once you pass emissions once, and get a collector's plate, you don't have to retake emissions. The trick is passing the first time-- I have a 406 with AFR big flow heads, an 825 CFM demon carb, big cam, and dual 3" exhaust with no cats or any emission equipment --

And even if I do find a way to pass -- there are those mobile emission testers set up. I heard that if you pass one of those things and they flag you for emissions, even with collector's plates -- they will give you a $100 fine and make you re-do emissions and suspend your registration until you do. So even if I did a motor swap, or something like that, to pass emissions to get the plates, I could run into trouble in the future.

-BTW, both of these cars are 1973 models. Neither has any emissions equipment whatsoever.

They don't do an underhood inspection here, it's a sniff test only. Although they do check your gas cap to make sure it's not venting too much vapor.

You would be surprised at how easy it is to pass. I would suggest a simple tune-up paying close attention to your plug gaps and making sure your cap and rotor are in good condition - double check your timing, maybe dump in some nox reducer, and go take the test. If anything, it will tell you how close you are to passing. Then go from there.

Based on a little research, here's what I've sort of figured out:

Once you pass emissions once, and get a collector's plate, you don't have to retake emissions. The trick is passing the first time-- I have a 406 with AFR big flow heads, an 825 CFM demon carb, big cam, and dual 3" exhaust with no cats or any emission equipment --

And even if I do find a way to pass -- there are those mobile emission testers set up. I heard that if you pass one of those things and they flag you for emissions, even with collector's plates -- they will give you a $100 fine and make you re-do emissions and suspend your registration until you do. So even if I did a motor swap, or something like that, to pass emissions to get the plates, I could run into trouble in the future.

-BTW, both of these cars are 1973 models. Neither has any emissions equipment whatsoever.

I do not think they do this. I passed one several times just before this last re registration and The computer had nothing about it. (fyi, my car has absolutely no emissions equipment on it anymore.)

never did my camaro but my luv i just took to a 81 older place down of broadway and i have gone twice now and passed both times i just tip the guy pretty good

They don't do an underhood inspection here, it's a sniff test only. Although they do check your gas cap to make sure it's not venting too much vapor.

You would be surprised at how easy it is to pass. I would suggest a simple tune-up paying close attention to your plug gaps and making sure your cap and rotor are in good condition - double check your timing, maybe dump in some nox reducer, and go take the test. If anything, it will tell you how close you are to passing. Then go from there.

if you bring it to the nasty little air care colorado places they do the underhood inspection, at least they did on my last time doing the test (Thank God for collectors plates hehe)

What do you think about using denatured alcohol added to the gasoline to help reduce emissions for the purposes of the test?

Do they care greatly about leaks?

Do I need full tailpipes (I have turn downs right now) for them to do the test? Do I need a catalytic converter to pass (I don't have one)?

Any tuning tips to pass that worked for you guys?

Want to have my best shot on the first try

thanks for your help

What do you think about using denatured alcohol added to the gasoline to help reduce emissions for the purposes of the test?

Do they care greatly about leaks?

Do I need full tailpipes (I have turn downs right now) for them to do the test? Do I need a catalytic converter to pass (I don't have one)?

Any tuning tips to pass that worked for you guys?

Want to have my best shot on the first try

thanks for your help


you only need what your car came equipped with. Tailpipes yes, they have to extend a certain distance past the cab, not sure how much though.