They really struggled with emissions back then. I had a 1967 400 HO parts car. I can remember the drilled ports in the 670 heads for the AIR tubes. Mine were plugged. Then I remember reading that Pontiac was able to eliminate the AIR system in 1968 by going to open chamber heads VS the closed chamber '67 heads. I did not see AIR again until the 1980 301 engines. My 1972 Catalina 400 had the TCS switch. It only allowed vacuum advance in high gear. I quickly eliminated that stupid idea.
