The Edelbrock red roller rockers #77760 small block chevy 3/8 stud 1.5:1 Wide body set of 16 ratio are manufactured in the USA from lightweight 7129 grade aluminum. The body is CNC machined then micro polished and anodized for durability. The trunnion race, roller pin and roller tip are centerless ground for superior quality. A high quality Torrington needle bearing fulcrum combined with a roller tip ensure smooth operation and performance. The full body design will accommodate up to 1.65" diameter springs. Thick-walled adjusting nuts and 4140 steel poly locks are included. Installation Note:Rocker geometry should be checked, making sure that the contact point of the roller remains properly on the valve tip and does not roll off the edge. Visual inspection of the rockers, valve springs, retainers, and pushrods should be made to ensure that none of these components come into improper contact with each other. If problems with valve train geometry occur, changes such as pushrod length may have to be made.