Quote:
Originally Posted by ToronadoGuyDenver
It is the correct carb. I have the original and the newly remanufactured carburator. I have the factory service manual and I did install the newly remanufactured motor and in fact, the car runs great. Just a little high on the CO and I've taken it to get looked at twice. I'm at a higher altitude and I've known some people to have had to have gotten the carb rejetted.
I have a choice at this point, have the original overhauled by a professional or take it back ino the shop.
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The "jetting" is controlled by the computer, which reads the O2 sensor and varies the duty cycle of the mixture control solenoid automatically. If you're at higher altitude, the system should automatically compensate. I don't even know if you can get different jets for the Electronic Qjet, since is uses special primary metering rods. Have you checked the dwell setting of the mixture control solenoid? There's a green single wire connector in the harness just in front of the carb. Connect a normal dwell meter set to the six cylinder scale. You will read M/C solenoid dwell in degrees. It should be slightly varying around 30 degrees. If it's fixed or if it's off from 30 degrees, you have a problem in one of the systems controlling the carb. Note that this control is very sensitive to adjustment of the throttle position sensor, adjustment of the park/neutral switch, proper functioning of the A.I.R. system, and a host of other parts.
The 307 is also very sensitive to other aspects of the system. For example, always change the oil just before an emissions test. Any residual gasoline that might have leaked past the rings will cause an increase in HC and CO. Be sure the evaporative cannister system is functioning correctly. What's the condition of the catalyst? If you just broke in a new motor, you may have contaminated the cat with oil blowby. Is the PCV system working properly.
If it's any consolation, the VIN Y 307 has the highest emissions failure rate of any engine in the EPA database. The Chevy 305 with the same electronic Qjet is in the number 2 position.