67 dart emissions

There has been much discussion about tuning for emissions, something that everyone faces in all states to some degree or another. Even in Colorado there was an emissions check before I got my 5 year classic license plate. Tuning to meet emissions standards is not hard, but it requires a sound engine to begin with. 360 heads on a 273 may lower compression enough to hurt combustion efficiency. Run a compression test and a leak down test to be sure the engine itself is sound. Make sure all cylinders are firing and that there is no bounce in the timing at idle or any RPM. This means plugs, points, wires, cap and rotor are all sound and working. Make sure there is no play in the distributor shaft and that the advance plate is clean and functiong (both vacuum and mechanical advance).And I stand by my point that more advance improves HC/CO emissions. The reduced timing in the late '60's and early '70's was done to reduce NOx emission as NOx goes up quickly as combustion temperature rises above 2200°F. Reducing timing to 0° or so reduced NOx. But in increased HC/CO. Improved combustion efficiency reduces these emissions which helps you meet tailpipe sniffing emissions tests. Plus increased ignition advance (to the point where knock is not heard though) increases fuel efficiency tremendously. I got my '67 383 4sp to pass '78 emissions standards in California, but it was a new tight build with 10.5:1 compression and a 284/484 Isky cam. I ran 10° initial advance and 37° total advance with a fairly steep advance curve all in at 2200 RPM. This engine would idle down to 400 rpm smoothly, a sign of good ignition and correct A/F ratio at idle.Hope this helps, and good luck.