Spark Plugs

  • Overview
  • Analysis
  • Electrode Gap
  • Electrode Gap Adjustment
  • Projection
  • Modified and Performance Engines
  • Heat Range
  • Operating Temperature
  • LPG Compatibility
  • Precious Metal
  • Installation
  • Resistor Spark Plugs
  • Racing Spark Plugs

Spark Plug Installation

Spark plugs are designed to operate at an optimal operating temperature and correct tightening is critical to the operation of a spark plug. The following two major problems commonly occur if the incorrect torque is applied:

  • Excessive Tightening > Thread breakage
  • Insufficient Tightening > Overheating

Installation Instructions for new Spark Plug:

1. Confirm that the thread reach of the spark plug is the right one for the engine.
2. Remove any dirt at the gasket seat of the cylinder head.
3. Tighten the spark plug finger tight first until the gasket reaches the cylinder head, then screw about 1/2 – 2/3 turn more with a plug
wrench. (Conical seat; about 1/16 turn more). Refer to diagrams below for full details.
5. If using a torque wrench, please refer to the table below.
6. Always remove and install spark plugs when the engine is cool.