Before you can take out and change the valve, the cylinder heads have to be taken off. You should begin by taking the cylinder head covers off and then follow by removing the rocker arms and the lash adjusters. Following this, remove both of the camshaft bearing caps and then the camshaft. Place Tool C-3422-B or C-3422-C Valve Spring Compressor on the valve, adding Tool 8519 Adapter if required, then use a tapping motion on the top of the valve spring to make the spring retainer locks easier to release. Take out the two halves of the spring retainer lock distrusting the valve spring compressor, as the valve spring may still have a lot of tension. When you remove the spring compressor, carefully get the retainer and spring out, look for burrs in the keeper grooves, remove them if present and then take out the valve from the cylinder head. Because intake and exhaust have the same type of valve stem seal, take it out and mark the valve for correct positioning while you keep track of which camshaft it came from. Springs on the valves should be tested and examined for reuse every time valve removal occurs. Check the condition of the valve springs and with Tool C-647, bring the 40.12 mm mark against the surface and pull on the torque wrench until you get a ping. The spring load is the multiplied by two from the reading. Look up the height and allowable tension for the assembly and use replacement springs if the others do not fit these specifications.