Why Choose Roller Rockers?
roller rocker ratio
The rocker arms used on Yella Terra and Street Terra roller rockers are infinitely stronger than standard pressed steel arms providing the best in resistance to bending and breakage under high spring pressures at high RPM's.
Pressed steel rocker arms, in high performance applications, are prone to failure, A high rate of fulcrum wear, flexing, cracking, splitting and breakage are common problems that will result in power loss or possible piston failure due to detonation of the incoming air/fuel charge. Other Yella Terra rocker components such as the trunnions, posi locks and bearings greatly enhance valve train durability in performance applications.
Reduced valve guide and seat wear
The traditional metal tip on standard rockers literally drags across the valve tip as the rocker opens and closes causing high side loading on the valve. This inside force leads to irregular and rapid valve, valve guide and valve seat wear in many engines. The roller tip on Yella Terra and Street Terra roller rockers eliminates this side loading action, as a result engines rev quicker and freer with a crisper exhaust note and maintain peak efficiency longer.
More power through less friction
The use of needle roller bearings at the rocker fulcurm combined with roller tip at the valve greatly reduces horsepower robbing friction in the valve train to provide a measurable power increase over standard rocker systems.
The reduction in friction with roller rockers has additional benefits of reducing the operating temperature and foaming effect of engine oil to provide a cooler running engine.
Valve train adjustment
Use of high performance hydraulic or mechanical camshafts requires some form of valve train length adjustment to achieve correct clearance and geometry. Adjustable roller rockers allow these corrections to be made quickly and easily.
Valve train stability
Yella Terra and Street Terra "Easy Fit" shaft and pedestal designs offer the most rigid rocker system without using restraining devices such as guide plates, screw in studs and stud girdles. The result is more consistent valve lift and vastly improved valve train reliability at substantially lower cost.