Valve Seats - Installing And Grinding Valve Seats - Danny's Engineportal
The mistake made is, to cut the exhaust seat at 30 degrees instead of 37.5 degrees. Because, reducing the contact point, will burn out the valve. Also, keep in mind that tool holders wear out. As a result, allow the cutter to tip during operation. The runout requirement is generally, between .001″ and .002″.