Race Hydraulic Flat Tappet Lifters feature Tighter plunger-to-body tolerances and premium one-piece pushrod seats. Super strict tolerances for the Mechanical internals optimize performance. Extra heavy-duty snap ring design increases lifter strength& durability. Pre-load can be set between .000"-.030" (recommended pre-load .000", additional .030" can be used to aid in tuning and possible lifter noise that may occur with .000" pre-load setting). Applications Chevrolet Small and Big Block - Specifications.842" Diameter‚104g Weight‚2.01" Seat Height.