Which spring measurement does NOT require replacement if it is out of specification?

In this context, the measurement of installed height does not require replacement if it is out of specification. Installed height refers to the distance the spring is compressed when installed in the engine, and it can vary due to factors such as wear and the way the engine has settled over time. Adjusting or compensating for installed height may be possible through shimming or other methods without needing to replace the spring.

In contrast, other measurements like pressure, free height, and squareness directly affect the spring's performance and function. For instance, spring pressure needs to meet specific values to ensure proper valve operation, while free height affects preload and torque conditions. Squareness is essential for alignment and even loading on the spring. If these measurements are out of spec, replacing the spring is usually necessary to maintain the integrity and efficiency of the engine operation.