Which tool is most accurate for setting engine timing?

The most accurate tool for setting engine timing is the timing light. A timing light allows a technician to see the ignition timing in real-time, as it synchronizes flashes of light with engine revolutions. By connecting the timing light to the number one spark plug and pointing it at the timing marks on the engine's harmonic balancer or flywheel, the technician can observe whether the timing is set correctly according to the manufacturer's specifications.

Using a timing light ensures that the timing is adjusted accurately, allowing for optimal engine performance. It measures the position of the ignition timing in relation to the position of the crankshaft, which is crucial for ensuring that the combustion process occurs at the correct moment in the engine cycle.

In contrast, while a torque wrench is important for achieving the correct tightness of fasteners, it does not serve to adjust or measure timing directly. A compression tester measures the compression pressure within the cylinders and is used for diagnosing engine health rather than setting timing. A dwell meter measures the dwell angle to determine the length of time the ignition points are closed in an ignition system, but it does not directly measure or set the engine timing itself. Thus, for the specific task of setting engine timing, the timing light is the most accurate and relevant tool.