During assembly of an improved phaser, a rotor bias spring is captured by a spring retainer that is fitted or formed into the cover, allowing the spring to be installed in a pre-load position and forming a sub-assembly that is then attached to the remaining components. Grounded and active spring tangs are captured in separate slots in the spring retainer. A pocket within the rotor receives the active tang of the bias spring. The pocket has a tapered bottom ramp that lifts the active tang from the slot wall in the retainer and positions the active tang within the pocket in a retarding direction. Lifting the active tang of the bias spring prevents friction between the spring and the retainer slot wall as would occur as the rotor moves in a retarded direction. In advancing, spring rotation stops when the active tang contacts the end of the retainer slot.