Thermostatic Valve
Thermostatic valve not operating at high ambient temperature (this prevents cool air from flowing through main body and flange into intake manifold to cool fuel-air mixture and inhibit fuel evaporation)
As the valve opens, it allows outside air to flow directly into the intake manifold, leaning out the rich air fuel mixture. Valve starts to open when engine compartment temperature reaches 140 F, or 60 C and fully opens at 167 F, 75C.