Valve Spring Dimensions And Valve Spring Pressure Load

WARNING: This page is about a different car, the 2004 Nissan Titan. However, it is still accessible from the selected car via links, so may be relevant.

Check valve spring pressure at specified spring height.
Standard: Intake and exhaust
1. Free height: 50.58 mm (1.9913 in)
2. Installation height: 37.0 mm (1.457 in)
3. Installation load: 165.8 - 187.0 N (16.9 - 19.1 kg, 37 - 42 lb)
4. Height during valve open: 28.2 mm (1.110 in)
5. Load with valve open: 314.8 - 355.0 N (32.1 - 36.2 kg, 71 - 80 lb)
If it is not within specifications, replace the valve spring.

Fig 1: Checking Valve Spring Dimensions And Pressure Load
Courtesy of NISSAN MOTOR CO., U.S.A.