What is the normal gap for spark plugs?
2 Answers
The normal gap for spark plugs is between 0.6 to 1.3mm. The larger the spark plug gap, the longer the arc generated during ignition, making it easier to ignite the air-fuel mixture in the cylinder, resulting in greater kinetic energy. However, as the gap increases, a higher voltage is required to penetrate the air during ignition, so different engines are matched with spark plugs of varying gaps. The spark plug is a crucial component of a gasoline engine's ignition system, which introduces high voltage into the combustion chamber and causes it to jump across the electrode gap to generate a spark, thereby igniting the combustible air-fuel mixture in the cylinder. A spark plug mainly consists of a terminal nut, insulator, terminal post, center electrode, side electrode, and shell, with the side electrode welded to the shell. If the spark plug is bent or the electrode is eroded into a round shape, it must be replaced with a new one.
I've been driving for thirty years, and the normal spark plug gap is typically between 0.7mm and 1.0mm, but the exact figure depends on your car model—older American cars might be closer to 0.8mm, while Japanese cars often hover around 0.9mm. If the gap is too wide, ignition becomes difficult, making cold starts a problem; if it's too narrow, the spark weakens, causing severe engine shaking and sluggish throttle response. I've experienced this before—adjusting it without checking the manual ended up burning out the ignition coil. I recommend checking every 20,000 kilometers or using a gap gauge, and regularly replacing spark plugs can save fuel and extend engine life.
