S park Plugs 5. Install the spark plug and tighten it to the specified torque. Take care not to over tighten it to prevent cylinder head threads from damage. SPARK PLUG ANALYSIS G643(E) Service Manual Chapter 2. Recommended Maintenance 26 Tightening torque 25~30 N•m State Contact point is black Contact point is white Description • Density of the fuel mixture is thick • Lack of air intake • Density of the fuel mixture is thin • Ignition timing is fast • Spark plug is tight • Lack of torque