Jims High Performance Roller Rocker Arms Features: Stock Ratio 1.625:1 Designed to reduce friction in the valve train and provide more horsepower with less heat in the top end Cast from 4340 chromoly steel and heat treated Jims roller rockers feature a 660 bronze bushing fit to .007-.0012 for the best wear resistance and oil control With a roller tip made from bearing grade material which reduces valve guide wear and valve tip galling Other features include a segmented parabolic pushrod cup which reduces friction at pushrod ends and also puts the load on the outer perimeter of pushrod ends Replaces OEM 17360-83 A and 17375-83 A Made in the USA