* 4.2L V6: This engine had 12 valves.
* 4.6L V8: This engine had 16 valves.
* 5.4L V8: This engine had 16 or 24 valves, depending on the specific configuration (3-valve or 2-valve per cylinder).
So there's no single answer without knowing the specific engine in the 2006 F-150.