What may be used to check the stem on a poppet type valve for stretch?

• A. Dial indicator
• B. Vernier caliper
• C. Depth gauge
• D. Micrometer

Answer: (D)

To detect small changes in the stem length of a poppet valve, you need a tool that can measure very fine, external dimensions with high precision. A micrometer is built for that purpose, offering measurements accurate to the thousandths of an inch (or hundredths of a millimeter) on slender parts like a valve stem. By measuring the stem at precise reference points and comparing to the specified length, you can determine if the stem has stretched beyond tolerance.

The dial indicator primarily measures movement or runout, not a fixed dimension. The vernier caliper is less precise for tiny elongations and may not resolve the small change you’re looking for. The depth gauge is suited for measuring depths, not axial length along a slender stem. For identifying small stretch on a poppet valve stem, the micrometer’s the most appropriate choice.