Emission test failure

[december2006]

Just failed Illinois emissions' test. Hydrocarbons @ 1692 (s/b<800). CO passed @ 5.4. Need to know how to adjust the SU carbs on a stock 1974 with emissions intact.

Thanks in advance.

Steve Bohler

[amgba]

You’ve got to lean-out the mixture. Using the manual, with the car warm, bring the jet up as high as you can to the bridge so less fuel is drawn in. Make sure your floats and their jets there are adjusted properly to prevent internal leakage and flooding.
Also consider going to a free-flow air cleaner or at least new stock ones. Use may improve the efficiency of the element for cleaning the air into the carb, but causes restrictions. Less restriction on the intake allows more air into the mixture and leans it out. For testing purposes, a light foam element filter can help (I used to remove the elements entirely from the stock air filters when I lived in New York and the B was young enough as to required yearly testing, as they never opened the covers to check).
I hope that helps you. Good luck.
Art Isaacs