Spark Plugs

Spark Plugs, designed by Harry Williams and manufactured by Williams in September 1951, is a single-player electro-mechanical pinball machine with a horse-racing theme, featuring mechanical backbox animation in which horses race as part of the game's presentation.

The machine offers five balls for five cents, an economical format aimed at wide accessibility. Gameplay includes two impulse flippers and eight pop bumpers, while three bells provide the game's sound effects. Artist George Molentin's horse-racing imagery, paired with the animated backbox mechanism, gives the game a distinctive sports-themed presentation uncommon among its contemporaries.

As an early example of Harry Williams' design work in the electro-mechanical era, Spark Plugs offers a glimpse into the mechanical ingenuity and accessible pricing strategies used by manufacturers in the early 1950s pinball market.