JP Performance Double Roller Timing Chain Set Keyway Adjustable Billet Steel Big Block Ford Disc Brake Caliper Z Design in Shell circulates air Plymouth GTX 70 71 Z Design in Shell circulates air throughout the shell utilizing large internal channels Features:Must be used with an MSD Ignition ControlPolished steel shaft is QPQ coated and guided by a sealed ball bearing for smooth operation at all rpmsMaintenance free magnetic pickup and precision reluctor create stable trigger signals throughout the rpm rangeCNC machined billet aluminum housing and billet aluminum base providing superior strength and great looksEasy to adjust mechanical advance with supplied springs and stop bushings (except locked out versions)Advance plate and weights are fine blanked from chrome moly steel and QPQ coated for friction reductionAdvance weight pins are staked and tig welded to the plateNylon pads ensure smooth operation of the advance weightsMechanical advance assembly can be locked out for crank trigger systems or racing applications For those that require a Torrington bearing fitted (such as race engines) then JP Performance Products also have them available six and four cylinder engines