Valve - Spring Squareness

Measure the out-of-square on each valve spring.
- Turn the valve spring and observe the space between the top of the valve spring and the square. Install a new valve spring if out of square. Refer to ENGINE- 3.8L & 3.9L or ENGINE- 4.6L (2V) or ENGINE- COBRA 4.6L (4V) or ENGINE - MACH1 4.6L (4V) for the procedure .
  
  Fig 1: Measuring Out-Of-Square On Each Valve Spring
  Courtesy of FORD MOTOR CO.