KB Hypereutectic SB Chevy Flat Top Piston Set - 4.030" Bore - 3.750" Stroke - 6.000" Rod Length 4240RD NOTE: The 20-121 is not

NOTE: The 20-121 is not designed for use with some early model Holley carbs

Ignition Plug and Play with GM 24x and 58x LSx engines

May not fit models with a body lift or transmission/ transfer case drop

5 wide paddle blades pull large volumes of air for maximum heat extraction

Hydraulic Adjustment

KB Hypereutectic SB Chevy Flat Top Piston Set - 4.030" Bore - 3.750" Stroke - 6.000" Rod Length 4240RD NOTE: The 20-121 is notModern piston design locates the top ring higher for improved performance. a high top ring operates at higher temperatures and requires a larger top ring end gap. To find the proper ring end gap, multiply your bore size by the ring end gap factor listed on the chart (i. e. , Street Normally Aspirated 4. 000" bore x . 0065" gap factor = . 026" total top ring end gap). Your hypereutectic performance piston will expand less than typical cast or forged