I have old memories of driving across the USA on fairly new and under construction interstates while burning leaded gas. Slight and not so slight "rolling coal" seen from tailpipes when hitting the Rockies. I saw drivers removing air filters and other methods to try to lean.
What spot and JaSAn said. You can tune way too lean and enrich by using a manual choke, like I’ve seen done with a lot of too lean small engines. Decades ago, Edelbrock’s were avoided for mainly Holleys because of a lack of understanding how to tune. Again, what spot said.
Before gasohol, I drove to the Rockies with no modifications, but the spark plugs and tailpipe showed slightly rich and probably not good for piston ring/cylinder wear. Now, with gasohol, the boiling point is so low it can actually boil the fuel out of the bowl with long pulls, parked or long idling. Also vapor lock. Electric pump helps, along with fuel line heat sleeves.
One crude method I’ve seen is to allow air to enter under vacuum, not through the venturis, to lean the mixture. Leaving a carb's ported vacuum fitting open can allow idling, yet also allow extra air into the manifold above idle. I’m so old, I remember removing the vacuum line from a windshield wiper motor to lean the mixture.
If not enough to correct the over richness, a manifold port can sometimes move more air. Under a really hard pull, vacuum can decrease to the point not much air can bypass the venturis for leaning.
I don't want to curse like others about the somewhat like fuel injection Variable Venturi carbs on USA vehicles around 1980, and I had good luck with the mainly British styles with the oil-filled reservoir. Fords variable venturi carbs worked great on V8 engines if looked after. They can still be had. So can a 4 to 2 barrel adapter plate.
Ford V8 flathead carbs had two drain plugs facing forward in the fuel bowl. Remove them, loosen the jets through the holes, then use a holding screwdriver to remove and replace the jets. Handy. Picture below. I installed one on a 2300 Ranger years ago using an adapter, to replace a gummed up emissions model that looked like a porcupine. Worked great.
Holley has a quick change jet kit for center hung floats, but at some expense.
Excuse the rambling. I’ll never forget my first coast-to-coast trip. Good luck.
