Centrifugal spark-advance controlling device

A centrifugal spark-advance controlling device in which a weight is subjected to centrifugal force caused by the revolution of a driving shaft to be opened against the elastic force of a spring member to thereby advance an advancing sleeve with respect to said driving shaft, comprising:

• a base plate fixed to said driving shaft, said base plate being provided with an elongated groove for guiding which serves as a guide for said weight to be moved in the direction of opening and an advancing plate fixed to said advancing sleeve,
• a position-determining pin extending downwardly from said weight to be engaged with an elongated groove for determining position in an arcuate form formed in said base plate and said elongated groove for guiding is of an arcuate form, said advancing plate being provided with an elongated groove for advancing which determines a relative advance angle of said advancing sleeve with respect to said driving shaft in association with said elongated groove for guiding, wherein said weight is placed between said base plate and said advancing plate and there are provided on said base plate a cylindrical projection for guiding which is inserted into said elongated groove for guiding to be engaged therewith and a cylindrical projection for advancing which is inserted into said elongated groove for advancing to be engaged therewith.