Factory assembled engines are not equipped with washers. (OEM engineers obviously did not take our kind of activity into account.) ARP headbolts for Chevy applications are sold with washers included. They are effective at avoiding galling in the area of contact between the head of the bolt and the cylinder head during torquing and they help the assembler achieve consistent torque pressures. They are especially valuable on aluminum heads. Washers are a plus in any application that is anticipated to have the heads removed frequently.