Dress up your Buick 401-425 Nailhead engine with these brand new Grade 8 ARP (American Racing Products) Stainless outside of the valve cover head bolts. This kit includes the 18 headbolts that are outside the valve covers. This kit does not include the special stud bolts for the accessory brackets or any of the bolts under the valve covers. These bolts are not only good looking, and don’t rust, but are super strong for your high horsepower needs and have a polished finish. These bolts have a tensile strength of 170,000 psi and are much stronger than the original bolts. This head bolt kit is the outside of the valve cover head bolts only.