Howdy, I have a 2bbl carb and can't get my car to pass smog. When they run the car @2500 the C/O level goes to 7.43 and this is too high to pass. The guy told me to retard the timing a little and turn the mixture screws in one turn each, but the car still failed. Now he says it must be internal carb problems. What could be wrong? The carb takes adjustment and it passes the idle portion of the test fine.