How is valve concentricity measured?

Valve concentricity is measured with a dial indicator because this instrument provides a precise method for determining how well the valve stem is aligned with the valve guide. A dial indicator can detect even minuscule deviations, allowing a technician to assess the uniformity of the valve's motion and its relationship to the engine's cylinder head.

Using a straight edge, while helpful for assessing flatness or alignment in some contexts, does not offer the necessary precision for measuring concentricity. Although visual inspection can help identify obvious issues, it lacks the accuracy needed to confirm concentricity. Similarly, relying on feel might give a rough idea of alignment but does not provide a quantifiable measurement necessary for effective assessment and potential corrective actions. This precision is crucial, especially in performance applications where valve operation directly affects engine efficiency and reliability.