Thermoquad tuning to pass smog

I have not read all the comments sorry if redundant. NOX is a buy product of combustion temp. The carb if really lean can cause this but lean is the direction of smog fix these days and back then. The EGR valve is the direct fix for NOX on that engine. Also the cat but EGR is what you need to check into. Make sure it is opening and all passages are clear and open and that there are no air leaks, if it leaks it can suck in more oxygen cause leaner hotter combustion Temps. Also make sure that the mechanical advance has not been speeded up with a recurve. This will cause higher combustion temperatures at a cruise. Retarded timing will run your engine hotter but it runs the combustion temp down. Ca. Smog suck good luck