Formula C was also an open wheeled SCCA racing class originating in the mid 60s, derived from the failed Formula Junior

Formula Junior

Formula Junior is an open wheel formula racing class first adopted in October 1958 by the CSI . The class was intended to provide an entry level class where you could use inexpensive mechanical components from ordinary automobiles...

 class. Formula C cars were very similar to Formula Juniors; Formula B was a similar class with uprated 1600 cc engines. Formula C cars were limited to 1100 cc engines. In the SCCA today, Formula Continental

Formula Continental

Formula Continental is a single seater, open wheel racing class in motorsport. It replaced Formula C as an SCCA racing class. Formula Continental includes three types of cars....

is the direct descendant of Formula C.