Used Flathead Ford V8 2 piece valve spring retainer, sold individually.  For 1951, 1952, 1953  Flathead V-8. Ford part numbers 1BA-6514 and 1BA-6507

Must be used with with short, matching, springs.  These retainers allow valve rotation, which may give longer service life.  They do not handle valve lifts over .350" very well.