Ford FE 390 427 428 Internal Balanced Fluid Damper Harmonic Balancer SFI 18.1 The Speedmaster design incorporates open-fin

The Speedmaster design incorporates open-fin spacing that promotes airflow through the radiator to enhance the cooling and help eliminate clogging

don't forget to get the correct transmission yoke for your application

They are for small and big block Chevys

but both factors can be equally important in a race car

The internal components are made from EN36 material as used in racing

Ford FE 390 427 428 Internal Balanced Fluid Damper Harmonic Balancer SFI 18.1 The Speedmaster design incorporates open-finUsing only three parts a laser welded sealed housing, an internal inertia ring, and highly viscous silicone fluid between the two these SFI approved Fluid dampers can control all crankshaft vibration, not just a limited frequency range. As a result, you get reduced wear on the main bearings and timing gear, more stable valvetrain operation, and less chance of crank failure.