Automotive Racing Products (ARP) Rocker Arm Nut Set 300-8249; Perma Loc 7/16 in. -20 0.560 in. Stud Girdle Polylock for Chevy 396 to 454 BBC

One of the more aggravating things found in many high performance engines is constantly having to re-adjust rocker arms. Until ARP introduced the patented Perma-Loc adjuster, there wasn't a "poly lock" on the market that you didn't have to continually tighten. There are several important reasons why ARP's Perma-Loc rocker arm adjusters won't loosen like others. First, the adjuster body is heat-treated all the way through (not just case hardened). This eliminates the thread "movement" common to others. Secondly, the threads are machinedexactly perpendicular to the bottom of the adjuster, so it seats evenly and applies pressure on a full 360 degree circle. Lastly, the set screw is machined flush on the bottom (not pointed) so it will have optimum contact on the rocker arm stud. You'll find ARP Perma-Loc's easy to use, too. The compact 12-point head is designed to hold your wrench in position while you lock the set screw with an Allen wrench. All in all, they're the best you can buy! WARNING: Cancer and Reproductive Harm. www.P65Warnings.ca.gov