How much clearance WP to Dampner?

My Dampner was slightly touching the WP. I am shaving the bottom hole of my Waterpump and its starting to get a little thin. I currently have .63 mm at the least. I have maybe a little more I can go but not much. Anybody have a Romac Dampner with a similar issue and how much clearance do you have

Thank You:SNSign:

Nobody with a similar issue.