Can anyone explain to me the purpose of part number 6 (insulator), on the diagram below? I found it in my parts box, apparently I forgot to replace it when I put my engine together. :doh: I don't have the Upper timing cover installed, because I am running adjustable cam gears and plan on tunning in a few weeks.

It doesn't appear to be important, I was just curious what it's for. I'll most likely put it back on with the cover, after tunning. I don't drive the car daily btw. Thanks in advance!