Olds V8 6.5 Harmonic Damper - SFI

This 6.5" damper is designed for Oldsmobile V8 engines, including 330, 350, 400, 403, 425, and 455 cubic inch displacements. It features an externally balanced design with a removable bolt-in counterweight, allowing for a neutral balanced rotating assembly. The damper includes the stock Oldsmobile accessory pulley bolt pattern and a Big Block Chevy bolt pattern for crank trigger systems. Machining may be required for Chevy pulley use. For 330 engines, the TDC mark needs repositioning. This damper fits late 400 and 425 engines; early 400/425 engines may require counterbalance modification by a balance shop. To ensure proper fit of stock accessory pulleys, the four mounting holes in the pulley must be drilled out using a Letter Size Drill "T", Fractional Size Drill 23/64", or Metric Size Drill 9MM.