The McCoy "9" glow-plug motor of .098 cuin. displacement was introduced in 1949. It was a very successful design, being both light and reasonably powerful by the standards of 1949. It was also quite sturdy, hence serving admirably as the first engine for many American modellers, who typically still remember it with great affection. Its success resulted in its remaining in production until 1956.

The McCoy “9” broke a number of significant design barriers for its creator Dick McCoy. It was his first-ever crankshaft front rotary valve (FRV) design, also being the smallest-ever engine from any designer to feature a ringed light alloy piston. It subsequently became McCoy’s first-ever model to feature a lapped piston following a 1950 design change. It served as the prototype for a long line of McCoy FRV sports engines which represented a complete departure from the racing-type models previously associated with the McCoy name. Finally, along the way it became the subject of one of Dick McCoy’s rare errors of judgement - his "Duro-Glo" cylinder head which represented an unsuccessful attempt to circumvent Ray Arden's patent of the commercial miniature glow-plug. All of this makes the McCoy "9" an unusually significant design despite its apparently humble status.

A detailed review and test of this cute little engine appears elsewhere on this website.