Cliff's Quadrajet Parts and Rebuild Kits
General Category => Quadrajet Carb Talk and Tips => Topic started by: track73 on November 09, 2013, 08:12:12 AM
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I went to get the '79 T/A tested so I can renew my veteran plates. It failed the single idle because the HC was at 967 ppm and it's only suppose to be below 350 ppm. The CO was real low at.26% and can be 3.50%. I was thinking that it is probably a little lean. I don't know which direction to go. I can rich-en the idle mix or maybe take the vacuum advance off the manifold and put it on ported and up the idle. Which would be the better option? This car has to be tested every two years and has passed in the past,but I forgot what the combination was. It has a Q-jet and a real mild "RV"cam ,headers, 2 cats and low compression.
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With such a mild set-up there would be no advantage to use manifold vacuum to the advance. It will make it much harder to get thru emissions, as it shouldn't need that much timing at idle. The factory knew this, and why most of those engines used ported vacuum to the advance, or devices in place to retard timing at idle, etc.....Cliff
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High HC, low CO? First guess: Lean misfire.
Richen mixture or find 'n' repair vacuum leak.
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Don't know where you are but I would suggest checking with your MVA to see if they offer a historic or hot rod class of registration...around here, they do and it saves not only a decent sum on the annual registration but also lets you bypass the inspection and emission issues...