The Phillips head machine screws that hold down the stamped steel valve covers on my '60 283-230, not only have the special reinforcing washers (washers with wings) under them but also a similarly configured cork pad under the washers. I've not seen these cork pads on any cars at events that I've attended so far nor does the NCRS TIM&JG mention them. Also, none of the popular catalogs list them. After 40 years, mine are in various stages of disrepair ranging from brittle, cracked, broken to missing altogether. Should I get a sheet of cork and get to work with an exacto knife or just forget them? Maybe a Survivor/Bowtie guy would comment.