Rocker Arm Jam Nut - 7/16-20 12pt.

The T AND D MACHINE Rocker Arm Jam Nut 7/16-20 with 12-point head is a precision fastener engineered for small-block engine builders and performance machine shops requiring exact rocker arm adjustment. This steel jam nut features black oxide finish for corrosion resistance and reliable holding power on rocker arm adjuster studs, a critical interface in valve train assembly where vibration and thermal cycling demand secure, repeatable clamping.

The 7/16-20 thread specification indicates a 7/16-inch diameter with 20 threads per inch—the standard metric for rocker arm adjuster hardware on small-block Chevrolet, Ford, and comparable platforms. The 12-point head design provides multiple engagement angles, reducing the risk of corner rounding when using standard or crowfoot wrenches during installation and adjustment cycles. Black oxide plating provides modest corrosion protection suitable for engine bay environments, though it does not offer the enhanced rust resistance of chrome or nickel plating. The individual unit weight of 0.01 lbs confirms the compact, lightweight profile typical of this hardware class.

This jam nut is essential for engine builders performing initial valve train setup, tuning rocker arm geometry, or replacing worn adjuster hardware. Whether you're assembling a stock replacement engine, building a performance street engine, or preparing a race engine for competition, maintaining secure rocker arm preload depends on quality fasteners that resist loosening under sustained RPM and temperature extremes. T AND D MACHINE is recognized for precision machine shop hardware, and this jam nut meets the exacting tolerances required for professional engine building work.