What is being checked on a valve spring during inspection?

During the inspection of a valve spring, checking the installed height is essential because it determines the effective functioning of the spring when it is in place in the engine. The installed height is the measurement from the spring seat to the top of the spring when it is installed but uncompressed. This measurement is crucial because it affects the amount of load the spring can exert on the valve. If the installed height is incorrect, it can lead to inadequate pressure on the valve seat, causing issues like valve float or incomplete sealing, which can negatively impact engine performance.

While the other aspects such as squareness, coil taper, and tension are also relevant to the overall condition of the spring, they do not specifically govern how the spring will function once installed. Squareness refers to how the ends of the spring meet the spring seat and can affect its alignment but is less critical than the installed height. Coil taper concerns the uniformity of the wire diameter along the coil, which can affect spring rates and performance but is secondary to ensuring the proper installed height. Tension refers to the load or force the spring can exert, but without the correct installed height, the tension alone wouldn't guarantee optimal performance. Thus, the installed height directly impacts how the spring will perform in its operational environment