ARP Head studs are made to be a direct replacement of factory head bolts for the JZ series engine. For installation you want to clean the threads in the block very well before installing the studs in the block. Apply ARP assembly lube to both sides of the washer and to the threads of the nut. you can snug up the studs on the block, just enough to bottom out the stud... We buy all new packages that come with the larger washers already included vs the old stock that comes with smaller washers... If you get for some odd reason an old package, you can reuse your OEM washers or call ARP customer support for replacement washers... YOU MUST KEEP THE BOX AS IT HAS THE LOT NUMBER AND BY WHOM IT WAS PACKAGED BY TO GET BETTER SERVICE.