Detent Spring

The detent spring in the M40 engine’s needle valve assembly is a small but crucial steel component that plays a vital role in providing precise control over the fuel flow. Designed to align with the knurls of the needle, this spring creates distinct positions or detents, allowing the operator to feel and hear tactile feedback as they adjust the needle valve. The detent spring’s strategic placement ensures that the needle valve remains securely in the selected position, preventing accidental movement and ensuring consistent fuel flow adjustments during engine operation. With its reliable material properties and careful engineering, the detent spring enhances the M40 engine’s user experience, enabling accurate tuning of the fuel-air mixture for optimized engine performance in model airplane applications.