It is rather complicated to perform any work on these engines and it is known that for many procedures, special tools are essential. Any operation where 
Timing Chain, camshaft, or 
Cylinder Head is used requires that the instructions should be well read and the disassembly must be done using special tools, otherwise the engine will be damaged. Start with IMG the removal of the valve lids and the timing chain lid. Subsequently, the timing chains as well as the 
Rocker Arms should be taken off. Camshaft thrust clearance must be determined with the help of a dial indicator; if the clearance exceeds the given indication, the camshaft or the cylinder head would have to be replaced. For 2-valve 4.6L engines, the camshaft sprockets will also need to be removed, the camshaft must also be locked before the sprocket bolt is loosened. As for welding the sprockets together, paint them in a way so that one's combinations don't get mixed up with the other's. Camshaft cap clusters must be repositioned to the former positions bearing the front and rear indications. Turning the bearing cap bolts to the left in the reverse of the tightening sequence, the bolts may only be slackened by a quarter turn at a time until they can be turned by hand. Take off the caps and raise the camshaft off the cylinder head gently and, if needed, starting it off with a little tap lightly. So perform the same procedure for the other camshaft that lies over set of cylinder head. The same procedure goes to the 3-valve 4.6L and 5.4L engine but always lock the camshaft before removing the sprockets and loosening the bearing cap bolt. For 5.0L and 6.2L engines, remove VCT assembly from the front end of each camshaft: then, taking care to loosen the bolts in the prescribed sequence, loosen the large camshaft cap first, and then proceed to the remaining camshaft caps. Raise the camshafts off of their bearing saddles, make sure that they are clean and that you remember which camshaft is which. Check for any wear on the cam lobes and bearing journals, measure the diameter of the journals using micrometer and also the lift of the cam lobe. Ensure that the 
Timing Chain Tensioner oil feed tube and reservoir is cleaned before injecting Plastigage at the oil clearance of each journal to check the wear of the timing chain.. For installation, any lash adjuster s an/or camshaft followers if removed, must be replaced in their positions. Use moly-base grease or camshaft installation lube to the camshaft lobes and bearing journals before fitting the camshaft(s). The camshaft caps should be assembled to their relevant positions, and all the bolts should be loosely fitted followed by the camshaft sprockets being in position before finally applying appropriate force. Turn the camshafts to the Neutral for 5.0L engines and then install the VCT assemblies and timing chains. Tighten all the bolts in the correct sequence and according to the correct torque but after a few minutes reverse the sequence in which the bolts were removed.