July 1: So it begins. Don't worry, this is not in the correct legal jurisdiction!

Valve Guide Inner Diameter

Measure the inner diameter of the valve guides in two directions where indicated.
- Refer to GENERAL SPECIFICATIONS .
Fig 1: Measuring Inner Diameter Of Valve Guides
Courtesy of FORD MOTOR CO.
If the valve guide is not within specifications, install a new cylinder head assembly. Refer to ENGINE - 3.9L article.