The Avia M 337 (originally designated the Walter M337) is an inverted six-cylinder air-cooled inline engine.

It was developed by the Czechoslovak company as a six-cylinder derivative of the four-cylinder M 332 engine, going into production in 1960.

An unsupercharged version of the M 337 is designated as the LOM M137.

Production transferred to Avia in 1964, and to Letecke Opravny Malesice (LOM) in 1992.

Data from Jane's All The World's Aircraft 1980-81 [1]