Small Block Chevy 3/8" top x 7/16" lower with or w/o guide plates - High Performance Series
ARP High Performance and Professional Series Rocker Arm Studs offer improved
reliability through longer thread engagement in the cylinder head and an extra
large radius for reduced flex. Special applications have been designed for
aftermarket heads to assure proper fit. High Performance Series are rated at
170,000 PSI while Professional Series are rated at 190,000 PSI.