Some grease one the outer and inner edge of the hole saw will catch a lot of it.

I had to enlarge the sending unit hole in mine to a bigger sender. After the hole was drilled I used a wad of masking tape wrapped stickey side out around the end of a coathanger. Worked great.

There are some pictures on the botom of this page.

http://www.clubhotrod.com/forums/sho...t=32947&page=5