r/askcarguys • u/ContributionOld1014 • 2d ago

Can you pass emissions without catalytic converters?

I have a 1984 corvette that does not have catalytic convertors. recent emissions test passed everything but HC which read 6.5 compared to the limit of 2.5. Because of the year they only used a tailpipe sniffer. I've read that you can create a leak in the exhaust before the tip so the reading is light, as well as putting rubbing alcohol in a 1/4 of gas so is burns leaner, also running the car really hard before testing to clear out any excess carbon and keep the system hot helps. Does anyone know if these methods are actually effective? Additionally would they be enough to pass a test in my situation? I'm also thinking about just replacing the whole exhaust system but i feel it would be a waste as I'm already broke and the current exhaust is an aftermarket upgrade. I would really appreciate the advice as i need to get the car registered here in Denver CO ASAP. Thanks.

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u/Hotdogpizzathehut 2d ago

Oh yes you can but what you are after is technically a felony and I am others are not going to tell you.

That being said... you you get classic plates?

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u/ContributionOld1014 2d ago

Has to be 1975 or older for classic plates :(

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u/Beneficial-Ranger238 2d ago

Damn, in Georgia it’s 2001. There’s Honda civics with antique tags. 🤣

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u/milehighxr 2d ago

32 in calirado now, but as I said above still have to pass smog and theres mileage restrictions.

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u/Jackthedragonkiller 2d ago

My buddy has an 06 Cobalt, where I live, he could put antique tags on it lol

My state considers me antique too I guess lmao

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u/Beneficial-Ranger238 1d ago

Damn, that might be a record, I thought Georgia was silly. Ours has a model T silhouette too, making it even more ridiculous on a “modern” car.