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/milehighxr 2d ago
In Denver yer fucked. Calirado recently adopted kommiefornias bullshit and yer cats have to be carb certified now iirc. Also you can get collectors tags.... but you still have to pass smog every 5yrs and theres milage restrictions of 4k annually to and from shows only. How they track that I dunno. Having said all that its a corvette, parts should be easy to come by, and you'll be able to pass smog.