Is there a significant difference between spark plug heat range 6 and 7?

[LeRemington]

There is a certain difference between spark plug heat range 6 and 7. The heat range of spark plugs includes nine levels, with 1~3 being low heat range, 4~6 being medium heat range, and 7~9 being high heat range. Therefore, spark plug heat range 6 belongs to the medium heat type, while heat range 7 belongs to the high heat type. The heat range 7 spark plug has a stronger balance between heat absorption and dissipation at the insulator skirt, allowing it to release heat from the combustion chamber more quickly, resulting in a lower operating temperature for the spark plug. Here are some precautions for replacing spark plugs: 1. Principles for replacing spark plugs: Generally, it is best not to change the spark plug heat range, as altering it can affect the engine's performance. However, if replacement is necessary, the principle is to use the original factory spark plug heat range as a benchmark and keep the change within one level up or down. Therefore, replacing a heat range 7 spark plug with a heat range 6 is feasible, but only if it is judged appropriate based on actual conditions. 2. Effects of changing to a different heat range spark plug: Changing the heat range to a higher or lower value can both have certain impacts on the engine. For example, if the heat range is reduced, incomplete combustion of the air-fuel mixture may occur, leading to symptoms such as insufficient power. It may even cause the spark plug to overheat due to inadequate heat dissipation, potentially resulting in phenomena like detonation. Conversely, if the heat range is increased, the spark plug's heat dissipation capability improves, causing the spark plug temperature to drop more quickly. This can lead to carbon buildup on the ignition tip, causing electrical leakage and preventing the spark plug from firing properly.