The first step in a valve servicing procedure is to check the valve guide for wear. If the guide is worn the valve will not seat properly allowing combustion leakage. If the guide is worn remove the existing guide and replace.
Once the guide is correct the seat can be cut to ensure concentricity of the seat to the guide. Also this is an opportunity to increase air flow by cutting three angle (three angle valve job – Check with your racing organization to see if this is legal).
Rotate the engine to top dead center with both valves down. Rotate the crankshaft clockwise from the flywheel side so that the piston is 1/4″ past TDC. Grind the end of the valve to acquire the correct valve lash as indicated on the cam card. Be sure that the valve end is ground perpendicular to the valve stem.
Note: the side cover must be installed and torqued during the entire process described. Install the valve springs and reinstall the remaining components.