WHAT IS A SMOG PUMP?

Something that is generally worthless and contribes nothing (IMO).

What they do is pump clean air into the exhaust stream which allows any fuel that wasn't burned in combustion to be burned off. Strictly an environmental thing. Kalifornia had the toughest laws concerning emissions, and smog pumps (along with other equally useless stuff) were required on cars sold here since 1972 or so.

Catalytic converters are a similar critter. The platinum plated pellets or wires promote burning of unburned fuel in the exhaust stream.

Steve

They reduce levels of carbon monoxide, hydrocarbons and nitrogen oxides, they require the engine to run lean enough to to still contain oxygen in the exhaust gasses to work properly. And ofcourse it must be using lead free fuel.