Patent ID: 7569978

Claim:
A spark plug for use in an internal combustion engine, comprising: a shell having an axial bore and a thread diameter (A); an insulator having an axial bore and a nose portion with an axial length (C), said insulator being located within said shell axial bore such that an outer surface of said nose portion is spaced from an inner surface of said shell axial bore by a radial distance (B) and said nose portion extends beyond said shell by a distance (D); a center electrode being at least partially located within said insulator axial bore and having a main shank portion and at least one radially reduced collar section, said collar section having an end face with a recess; a noble metal tip having a sparking surface, and; a ground electrode attached to said shell; wherein said noble metal tip is located in said recess such that said noble metal tip sparking surface extends beyond said insulator by a distance (M) and; wherein: 10 mm≦A≦14 mm; 8 mm≦C≦20 mm; 0 mm≦B≦3 mm; 0 mm≦D≦6 mm; and 1.5 mm≦M≦3.5 mm.