Are Bosch Spark Plugs pre-gapped at the factory?
A. Most Bosch Spark Plugs are factory pre-gapped for popular vehicle applications. The gap measurements are indicated either on the box, or by the part number located on the spark plug shell. X suffix = .044″ Y suffix = .060″ Z suffix = .080″ Gaps should never by adjusted on Platinum+4 or Platinum2. Bosch Platinum+4 and Platinum2 have factory pre-set gaps, and should never be gapped by the installer. Bosch Platinum and Super Spark Plugs also have factory-set gaps. For most plugs, the setting is shown on the plug package. These gaps are correct for the most popular applications of these plugs. There are applications, however, for which the gap setting has to be adjusted according to the vehicle manufacturers specifications. To avoid damage to a spark plug in the process of adjusting the gap, it is important to follow these guidelines: To widen the electrode gap, use a tool that only pulls back the ground electrode, without applying pressure to the center electrode. The tool must not be