Originally Posted by Hugginsauto

After replacing timing chain. It's still has some slack when you rotate the motor every now and then. I have the chain marked like its suppose to and lined up the crank mark and cam mark. Not sure why it's doing this.

Originally Posted by DYNOTECH

Ok Listen up. I have built/toredown hundreds of these 4.6 engines. A lot of good info above but here is the easiest way I've found. Before you remove the chains on these engines rotate the crankshaft so the keyway is at 12:00. At this location all the pistons are down far enough in the bores so you can't bend the valves when you rotate the cams with chains removed. Now do not, I repeat do not move the crank again until the cyl heads are reinstalled and both chains with tensioners etc.are completely reinstalled and tensioner release pins are removed. Remove the chain tensioners,chains, cyl heads, etc. Do whatever you have to do to work on the engine. Now reinstall the cyl heads. Look for two off colored chain links on each chain. These start out as copper color but get discolored as the engine ages. If you cannot find them then mark one link and count equal number of links from that link and mark it also. You want the same number of links between both timing marks on the same chain. Now install one the chain with the chain timing mark on the CRANK timing gear timing dot. Move the chain by hand up to the cam timing gear and rotate the cam gear ONLY (use wrench on cam gear bolt) to line up the timing chain link with the cam gear timing dot. Install the tensioner leaving the tensioner retaining pin in place yet. Now perform the same for the rightside head. Visually recheck that all 4 chain timing marks are lined up with all four gear marks. Then release the tensioner pins. You can now rotate the entire engine by hand. If everything was done right you are now in perfect time and no valves have been bent. My concern with your engine right now is that you may have bent valves. Look for valve marks on the piston domes. Even if there is a slight mark where a valve hit the piston dome the valve is probably bent and will have to be replaced. I wrote version of this procedure up for the Ford repair manual years ago but it was rejected because I was told Ford wanted to sell the cam retainer tools to the dealers. Good luck.