Date registered: Jan 2006
Vehicle: 73 280SE 4.5, 71 300SEL, 03 BMW Z4, 72 Fiat 850, 80 Triumph TR7, 85 Porsche 911
Location: DC Area
Mentioned: 1 Post(s)
Quoted: 95 Post(s)
The big one with the screw is your idle adjust. The other one acts as an air bypass valve, though the nomenclature escapes me. If you go to the online resources portion of the forum, there are articles uploaded that will give you an in depth overview of the engine.
Aside from obvious displacement differences between the 4.5 and 3.5, both are nearly the same, and the fuel, gas and air management systems identical.