i have an 83 Z28, 305 with the quadrajet. I recently failed emissions. The carbon monoxide readings were almost twice the allowed standard, i passed on hydrocarbons but not by much. Nox passed, readings were well below the allowed standard. I had it good and warmed up before testing, drove around for quite a while and kept in running while i was in line at the station, so i know it was hot enough. What do you guys think the prob is? Cat converter maybe? The O2 sensor was replaced last year and the carb is about 2 years old. I just replaced the air filter and gas cap. Maybe time to do plugs and wires too?

thanks

 

I don't know anything about tuning carbs for emissions....But how old is your cat? The original?

Put a new Magnaflow cat on my 87 TPI a couple of years ago & my car runs cleaner that most '09 cars, even at 200,000 miles & no smog pump!