ARP 202-4301 Pro Series Head Studs Nissan RB20, RB20DET, RB25, RB25DET

R32, R33, R34

8740: 8740 chrome moly is seen as a good tough steel, with adequate fatigue properties for most racing applications, only if the threads are rolled after heat-treatment, as is ARPs standard procedure. Chrome moly can be heat-treated to deliver tensile strengths between 180,000 and 200,000 psi.
This ARP head stud kit uses premium grade 8740 chrome molly. Each stud is placed vertically into special racks and precisely heat-treated to 190,000 psi. This procedure ensures complete heat penetration and the results are far superior.