Method of producing engine

A method of producing an engine, the engine comprising a partition member separating an auxiliary chamber from a main combustion chamber, a spacer that is disposed in an inside of the partition member, and a spark plug that is mounted to the partition member,

• the partition member comprising a cylindrical body, a hemispherical-shell-shaped end portion that is disposed at an end of the body, a first concave surface that is disposed at an inner surface of the end portion of the partition member, and an internal thread that is disposed on an inner peripheral surface of the body,
• the spacer having a second concave surface that is disposed on a side facing the first concave surface of the end portion of the partition member, and a first external thread that is disposed on an outer peripheral surface of the spacer and that is screwable to the internal thread of the body,
• the spark plug having a second external thread that is disposed on an outer peripheral surface of the spark plug and that is screwable to the internal thread of the body,
• the method comprising:
• a first step of attaching the spacer to an inside of the body of the partition member by screwing the first external thread of the spacer and the internal thread of the body of the partition member to each other;
• and
• a second step of, after the first step, attaching the spark plug to the partition member by screwing the second external thread of the spark plug and the internal thread of the body of the partition member to each other.