There are very few carb'd cars on the road these days in the USA. They were mostly phased out in the 80's and 1990 was the last year of passenger cars that had carbs (and there were only 4 or 5 if I recall)

The problem is you can drive a vehicle that's burning coolant or oil and just spewing a cloud behind it and nothing is really stopping you. I'm not sure if you can actually get a ticket for it or not.

> There are very few carb'd cars on the road these days in the USA.

Yeah, there are less, but on a summer weekend in Southern California you can expect fumes from a number of car-culture enthusiasts and their cars.

My favorite : Carbureted rotaries. The smell of unbalanced air-fuel ratio plus the smell of motor oil being burned in combustion. It's like the two-stroke of the streets. Even better when it has lost a coolant seal and you get that nice sticky white-blue coolant component to the noxious cloud left behind.

Yes, I'm aware.

The thing is, living in Michigan, I notice a lot more older carburated trucks than I do smoking modern vehicles...

They tend to be the worst, but they're not terribly plentiful. The bigger culprits are those oldish (10-20 years old) vehicles that have busted (if not removed) emissions control systems. As long as you enforce the emissions standards in effect the year the vehicle was built, you can get around a lot of the grandfathering issues.

Yes, every time I'm behind or passed by a "classic" older car with carburetors, even one that has been restored and looks like new, I'm surprised by how clearly I can smell the exhaust. By contrast modern cars emit almost no detectable smell. Hard to belive that pre-1980s all cars had exhaust odor like that, I certainly don't remember it from my childhood.

You don't notice it when you are used to it.

Pre '75 there was nothing to control oxides of nitrogen, which smell pretty awful, and combustion was never clean enough back then to control volatiles and hydrocarbons. I think all they had were secondary air injection, which was prone to failure and subsequent removal

You may not remember the smell, but do you remember the color of the L.A. skyline?

I guess the average carbureted vehicle on the road today is being run by someone with the mindset that the engine should run great and develop lots of power. Back in the day more people would have set them up leaner.

The ideal air fuel ratio for gasoline engines is 14.64:1. It hasn't changed. Running an engine too rich wastes fuel and reduces power, too lean causes detonation and can destroy it. Electronic fuel injection more precisely meters the fuel which keeps combustion closer to ideal. Carbureted vehicles are generally tuned as close as possible to ideal but it's always better to go slightly rich than slightly lean.