A method of forming a spark plug for being threaded into a cylinder head and extending into a combustion chamber for providing a spark to ignite a combustible mixture of fuel and air in the combustion chamber, comprising the steps of: providing a shell formed of metal extending along an igniter central axis (a i) from a shell upper surface to a shell lower surface and including a shell outer surface between said shell upper surface and said shell lower surface, providing a ground electrode formed of an electrically conductive material, attaching the ground electrode to the shell lower surface, the method being characterized in that it further comprises the steps of: predetermining an angle (α) of threads to be formed in the shell outer surface relative to the ground electrode, providing a thread forming apparatus for forming the threads at the predetermined angle (α) relative to the ground electrode when the ground electrode is disposed in a predetermined position relative to the thread forming apparatus, using an orientation tool to dispose the ground electrode in the predetermined position relative to the thread forming apparatus, and forming the threads in the shell outer surface at the predetermined angled relative to the ground electrode for allowing the ground electrode to be disposed in a predetermined position in the combustion chamber when the shell is threaded into the cylinder head, and wherein the orientation tool includes a tool outer surface extending longitudinally along a tool central axis (a t) from first end to a second end and includes a thread orientation feature extending transverse to the tool outer surface and wherein the step of using the orientation tool includes: disposing the orientation tool in a predetermined location relative to the thread forming apparatus such that when the ground electrode contacts the thread orientation feature the ground electrode is disposed in the predetermined position relative to the thread forming apparatus, aligning an igniter central axis (a i) of the shell with the tool central axis (a t), disposing the ground electrode along the tool outer surface, rotating the shell relative to the orientation tool until the ground electrode contacts the thread orientation feature, and forming the threads in the shell outer surface by the thread forming apparatus while the ground electrode contacts the thread orientation feature. providing a shell formed of metal extending along an igniter central axis (a i) from a shell upper surface to a shell lower surface and including a shell outer surface between said shell upper surface and said shell lower surface, providing a ground electrode formed of an electrically conductive material, attaching the ground electrode to the shell lower surface, the method being characterized in that it further comprises the steps of: predetermining an angle (α) of threads to be formed in the shell outer surface relative to the ground electrode, providing a thread forming apparatus for forming the threads at the predetermined angle (α) relative to the ground electrode when the ground electrode is disposed in a predetermined position relative to the thread forming apparatus, predetermining an angle (α) of threads to be formed in the shell outer surface relative to the ground electrode, providing a thread forming apparatus for forming the threads at the predetermined angle (α) relative to the ground electrode when the ground electrode is disposed in a predetermined position relative to the thread forming apparatus, using an orientation tool to dispose the ground electrode in the predetermined position relative to the thread forming apparatus, and forming the threads in the shell outer surface at the predetermined angled relative to the ground electrode for allowing the ground electrode to be disposed in a predetermined position in the combustion chamber when the shell is threaded into the cylinder head, and wherein the orientation tool includes a tool outer surface extending longitudinally along a tool central axis (a t) from first end to a second end and includes a thread orientation feature extending transverse to the tool outer surface and wherein the step of using the orientation tool includes: disposing the orientation tool in a predetermined location relative to the thread forming apparatus such that when the ground electrode contacts the thread orientation feature the ground electrode is disposed in the predetermined position relative to the thread forming apparatus, aligning an igniter central axis (a i) of the shell with the tool central axis (a t), disposing the ground electrode along the tool outer surface, rotating the shell relative to the orientation tool until the ground electrode contacts the thread orientation feature, and forming the threads in the shell outer surface by the thread forming apparatus while the ground electrode contacts the thread orientation feature. disposing the orientation tool in a predetermined location relative to the thread forming apparatus such that when the ground electrode contacts the thread orientation feature the ground electrode is disposed in the predetermined position relative to the thread forming apparatus, aligning an igniter central axis (a i) of the shell with the tool central axis (a t), disposing the ground electrode along the tool outer surface, rotating the shell relative to the orientation tool until the ground electrode contacts the thread orientation feature, and forming the threads in the shell outer surface by the thread forming apparatus while the ground electrode contacts the thread orientation feature.