Radial gap high thread spark plug

A spark plug located in a generally cylindrical spark plug receiving bore in an internal combustion engine, the bore communicating with a combustion chamber of the internal combustion engine and including a threaded portion and a seat portion which is located closer to the combustion chamber than the threaded portion, the spark plug comprising:

• a center electrode having a cylindrical body with a tip at one end and a terminal near the other end;
• an insulator radially surrounding the center electrode and having a substantially cylindrical body;
• and
• a ground shield surrounding said insulator including near one end a ground electrode having an annular opening formed therein which defines with said center electrode tip a radial spark plug gap;
• wherein
• the outside of the annular opening is slightly above and radially spaced from the center electrode tip;
• said ground shield has, on the end away from the ground electrode, a threaded portion having threads that are matched with the bore threads,
• said ground shield has a portion between the threaded portion and the ground electrode which provides a seal between said ground shield and the seat portion of the bore to establish an electrical ground between said ground shield and the engine while at the same time sealing the combustion chamber from the surrounding environment;
• said ground shield is formed from a first part which includes the threaded portion and a second part which includes the ground electrode;
• and
• said first part and said second part fit around said insulator and are deformed during manufacturing to be in mechanical engagement with each other and with said insulator to secure said first part, said second part, and said insulator together as a unitary assembly and against any relative movement.

A spark plug located in a generally cylindrical spark plug receiving bore in an internal combustion engine, the bore communicating with a combustion chamber of the internal combustion engine and including a threaded portion and a seat portion, the spark plug comprising;

• a center electrode having a cylindrical body with a tip at one end and a terminal near the other end;
• an insulator radially surrounding the center electrode and having a substantially cylindrical body with at least first and second diameter sections separated by a shoulder;
• a ground shield surrounding said insulator first diameter section and including near one end a section located proximate the insulator shoulder and a ground electrode extending from the other end having a portion thereof including an annular opening which is spaced axially further away from said insulator than the tip to define with the center electrode tip a radial spark gap;
• and
• an annular retainer surrounding said insulator second diameter section and including a portion having threads that are matched with the bore threads, the annular retainer providing a seal between the ground shield and the seat portion of the bore to establish an electrical ground between the shield and the engine while at the same time sealing the combustion chamber from the surrounding environment.