In a stud-mount rocker arm arrangement, the stud bears the brunt of the load imparted by the valvespring and pushrod. In a shaft-mount rocker system, the rocker pivots around a central shaft that's bolted to the cylinder head. With this setup, the shaft absorbs most of the valvetrain load, reducing deflection and increasing durability and high-RPM stability. (Photo courtesy of Comp Cams)
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