550" lift double valve spring kit for 1948-'84 Harley-Davidson® panhead and shovelhead engines.
- Includes 4 inner springs, 4 outer springs, and 4 aluminum top collars.
- Use with stock-style bottom collar, valve guides, valves with stock 3/8" stem, and stock keepers.
- Compatible with thin-stem valves if thicker keepers that maintain correct valve stem-top collar engagement are used.
- Late single bottom collars are included for use in S&S cylinder heads for shovels and stock late 1981–'85 heads.