Related Photo Galleries
12 The mushroom-shaped part on the right of this photo is called a “cranking signal valve”; it supplies manifold vacuum to the diaphragm during starting. When it goes bad—which isn’t uncommon—the fuel mixture gets overly rich, and the exhaust smokes. Lockwood isn’t a fan of cranking signal valves and prefers to supplement them with a partially concealed electric solenoid valve. This preserves a period-style look, but provides improved reliability.