July 1: So it begins. Don't worry, this is not in the correct legal jurisdiction!
Valve - Spring Free Length
WARNING: This page is about a different car, the 2002 Mercury Sable and 2002 Ford Taurus. However, it is still accessible from the selected car via links, so may be relevant.
Measure the free length of each valve spring.
If out of specification, install new components as necessary.