These are the alternatives by JIMS: Shovelhead Roller Rockers with a slightly higher ratio of 1.50 : 1 that yields more valve lift (stock on 1980-84). Cast from 4340 chrome moly steel then heat treated and equipped with precisely fit bronze bushings for stock rocker arm shafts. Segmented parabolic pushrod cups reduce friction at the pushrod ends and allow full oil pressure at the tip. The valve side features a roller tip made from bearing grade material to mimimize valve guide wear and valve tip galling.