Air injectors to meet US smog regs? Was a common way to do it back then, air pump driven off the front pulley pumping air into the exhaust manifold to get more complete combustion and cleaner emissions.
This sounds like a very likely explanation to me! Ive had a couple of 80s American cars and this featured on them. they had holes in the head above each exhaust port with a threaded adaptor screwed into it and a metal pipe leading off which eventually wound up at the affectionately named "smog pump" I'm not sure that carbs in general couldn't meet US emission standards, my 85 Oldsmobile Custom Cruiser station wagon had the full smog pump kit, electronic ignition and a hulking 4 barrel Rochester carb on its 305 cu in V8, all of it OE. Not sure why they bothered, the rotten thing only produced about 140bhp and did around 8mpg, I didn't keep it long! A later Cadillac Seville that I inherited from my father in law had a fuel injected but smaller V8 that was positively eco friendly by comparison, according to it's trip computer, it could do 26 miles per (US) gallon at 65mph cruise. This car also had the full emission gear fitted and working. But the results it produced on British MOT testing equipment were not all that good!