31. A common upgrade for a crossflow head engine is to use 351 Cleveland roller tip rocker arms . 32. It replaced the standard pullrods with rocker arms that activated vertical coil springs mounted behind the gearbox. 33. The primary rocker arm contains the VTEC switching piston, while the secondary rocker arm contains the return spring. 34. Depending on the design used, the valves are actuated directly by a rocker arm , finger, or bucket tappet. 35. The primary rocker arm contains the VTEC switching piston, while the secondary rocker arm contains the return spring. 36. The F7502 was central to the success of the L20, though it suffered from repeated rocker arm failures. 37. The suspension was designed around a series of rocker arms instead of the usual set up of wishbones. 38. The shovel engine does not have covers, per se, but rocker boxes and rocker arms which pivot on shafts. 39. Like all other Harley Davidson engines, the Shovelheads use pushrods to raise the rocker arms and open the valves. 40. VTEC is a complex system of camshafts and rocker arms that actually change cam-lobe profile as engine revs climb.
