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69GMCLonghorn · 09-21-2009, 05:33 PM

You went the wrong way. Excessive carbon monoxide indicates a LEAN mixture, not fat. So you were running lean at idle on the first test and OK in the midrange. On the 2nd test, you got the idle mixture right, but something affected the midrange and caused you to run lean under a load.

Excessive Hydrocarbons indicate a fat mixture. Edelbrocks typically run leaner than Holley's from my experience. Richen it up, and possibly jet it up one size if possible and you may pass. Also, try running some marvel mystery oil through the gas and oil per the bottle's recommendations. Not sure if that will work, but if it's been sitting for a while, I think it's supposed to clean things out.

09-21-2009, 05:33 PM	#2
69GMCLonghorn Registered User Join Date: Dec 2006 Location: Porter Ranch, CA Posts: 978	Re: Emissions fail - any advice You went the wrong way. Excessive carbon monoxide indicates a LEAN mixture, not fat. So you were running lean at idle on the first test and OK in the midrange. On the 2nd test, you got the idle mixture right, but something affected the midrange and caused you to run lean under a load. Excessive Hydrocarbons indicate a fat mixture. Edelbrocks typically run leaner than Holley's from my experience. Richen it up, and possibly jet it up one size if possible and you may pass. Also, try running some marvel mystery oil through the gas and oil per the bottle's recommendations. Not sure if that will work, but if it's been sitting for a while, I think it's supposed to clean things out. Last edited by 69GMCLonghorn; 09-21-2009 at 05:35 PM.