What tool is used to set the clearance between the valve stem and rocker arm?

The correct tool for setting the clearance between the valve stem and rocker arm is the feeler gauge. This tool is specifically designed for measuring small gaps or clearances, which is crucial when adjusting valve lash in an engine.

Using a feeler gauge allows an operator to insert metal blades of known thickness between the valve stem and rocker arm to determine if the clearance is within the specified range. If the gap is too small or too large, adjustments can be made accordingly to optimize engine performance and ensure proper valve function. This precision is critical, as incorrect clearance can lead to poor engine performance, excessive wear, or even engine damage.

Other tools, such as calipers, are more suited for measuring external dimensions rather than precise gaps, while a torque wrench is used for applying a specific torque to fasteners, and a socket set is a collection of tools for loosening or tightening nuts and bolts. These tools do not serve the purpose of accurately measuring the clearance necessary for the valve and rocker arm adjustment.