High-speed pullover/air-bleed system - enriches the fuel mixture at high RPMs.

Idle-speed temperature compensation - increases the idle speed at long stand-stills to cycle the water pump faster to cool the engine. Not present on all 2150's.

Throttle-actuated bowl vent valve - I guess you could consider this smog equipment in the sense that it keeps fuel vapor from reaching the atmosphere; it's part of the evaporative emissions system.

Relocated choke pulloff - two ways to do the same thing.