Before completing installation, which step is essential regarding spark plugs?

Checking the heat range before completing the installation of spark plugs is crucial because the heat range determines how quickly the plug can dissipate heat from the combustion chamber. Each engine requires a specific heat range to operate efficiently; using a spark plug with an inappropriate heat range can result in problems such as pre-ignition, detonation, or fouling. If the temperature of the spark plug is too high, it may lead to overheating, while too low of a heat range might prevent the plug from reaching the necessary temperature to burn off carbon deposits effectively.

Ensuring that the correct heat range is used is essential for optimal ignition performance, fuel efficiency, and the longevity of both the spark plugs and the engine. This step aligns the spark plug's characteristics with the engine’s design, making it a paramount part of the installation process.