Looking for someone with a little more know how on milling and ptv clearance. Im looking to get my 243 heads mulled for my ls1 looking to get 11:1 compression just wondering how much it'll need to b milled to get that compression and if it'll have any piston to valve clearance issues? Thanks for the help

 

You'll never know until you check. Roughly .0065 milled = 1 cc removed on cathedral port heads. I suggest leaving them un milled, check ptv and mill accordingly.