This standard is applicable to the main dimensions and specifications of M14×1.25 flat-seat spark plugs with medium and long screw-in lengths for electric spark ignition engines and their cylinder head mounting holes.
GB/T 6786-1986 history
2012GB/T 6791-2012 Road vehicles.Spark-plugs and their cylinder head housing.Basic characteristics and dimensions
1986GB/T 6786-1986 Spark plug M14*1.25 with flat seating and cylinder head housing
GB/T 6786-1986 Spark plug M14*1.25 with flat seating and cylinder head housing was changed to GB/T 6791-2012 Road vehicles.Spark-plugs and their cylinder head housing.Basic characteristics and dimensions.