Bolt-On Shaft Mount Rocker Arms that Perform!One of the best improvements in racing rocker arms in over 20 years, Crane Cams’ Shaft-Mount rockers eliminate ''bearing inertia'' and friction with a unique Polymer Matrix Bearing and Quick-Lift main body that increases valve opening-rate!
Crane's engineers discovered that a significant amount of energy was consumed every time a needle bearing changes direction. Moreover, they found that because rocker arms swing back and forth on a relatively small arc, in time the needles wear unevenly-a ''flat'' spot is worn.
To overcome this, they called on a new aerospace composite bearing that allows the rocker arms to literally ''float'' on a thin film of oil-eliminating parasitic loss from bearing reversal, and also reduces unit loading. Since the composite bearings are thinner than needle bearings, shaft cross-section has been increased 100% over the competition for additional stability. In another departure from the norm, a special aluminum alloy was employed that maintains its strength and resists deflection at the elevated temperatures (200-300° F) where rocker arms operate (instead of using ''aerospace'' alloys designed for sub-zero flight conditions).
The bodies have been profiled machined to eliminate all unnecessary weight and are clearanced for valve springs up to 1.800'' in diameter. They're 8 grams lighter (per pair) than the competition. Installation is a simple bolt-on for all high performance aftermarket heads, while OEM cast iron Chevy heads will require machining of the rocker arm stud bosses. The rocker arms are easily adjusted with a 12-point box wrench and hex key (no special tools required). This is one of those situations where ''space age'' technology has made a revolutionary new design possible.
Instead of relying on current popular needle bearings, Crane engineers have discovered a new composite bearing that provides the necessary support while significantly reducing friction and resistance. Consider that the pivoting actions of a rocker arm cause the individual ''needles'' to rotate in that direction. When the rocker reaches the apex of its travel and starts coming down, the bearings must reverse direction. And so it goes cycle after cycle. Crane's composite bearings are not directionally influenced, and have been Dyno Proven to provide up to 20 HP increases!
Moreover, use of the thinner composite bearings allows Crane to increase shaft diameter, which also contributes to improved valve train stability and reliability. It's a win-win deal!
