Professional Products PowerForce harmonic dampers are extremely durable—and economically priced. They're built with a bonding process which adheres the elastomer to the I.D. of the inertia ring and the O.D. of the hub, utilizing a strong adhesive along with an improved elastomer to create a much stronger bond. PowerForce dampers also feature white, easy-to-read timing marks against a painted black background. Each unit is accurately balanced and closely machined for the correct fit. Dozens of models are available for applications from 1955 and up. Choose the size, material, finish, keyways, and other options recommended for your vehicle.

Oldsmobile Harmonic Damper 6.5" V8 350/400/403/425/455. This is an externally balanced damper with a bolt-in counterweight which can be removed for a neutral balanced rotating assembly. This damper will work on 330/350/400/403/425/455 cubic inch Old's engines. The damper features the stock Old's accessory pulley bolt pattern as well as a Big Block Chevy bolt pattern for those who may want to run a crank trigger system. Use of Chevy pulleys will require some machining to damper. Note: On 330 engines, TDC mark must be repositioned. This damper fits late 400 and 425 only. Early 400/425 engines have a different counterbalance than provided. A good balance shop can modify counterbalance to work correctly on early 400 or 425 engines.