Re: doing head gasket on 4.7 help
Pull your front cover to expose all your timing componenets then do the following...
Roll your crankshaft over till your back at TDC 1 (which off the top of my head its like 1 o' clock ish with the key on the crankshaft. You want your V8 stamps on each cam gear to be at the 12 o' clock position on each head. Now looking at the idler sprocket in the middle (the idler is driven by 1 chain and drives both camshafts, so 3 chains) there is three openings in the face of the gear (slots). These slots should be in the 12, 4 and 8 o' clock positions if your engine is at TDC #1, there is a tool that has long fingers that stick through the bottom two and hold all the chains in their position on their sprockets while a latch inserts in the top hole to keep the tool firmly in place during the process. From there take some brake clean and spray everything off and get it all clean (chains and sprockets). take a paint pen and mark the correlation between each cam gear and the chain (mark a link on the chain and exactly where it is on the cam gear. So long as you find a way to keep the chains on the idler sprocket without having the "special tool" all that you have to do when you go back together is line up your paint on the chain and sprocket bolt it all up, pull the pins out of your tensioners then roll it over 2 times and check to make sure all your marks are where they should be.
from there its rippin' and tearin' unbolt the tensioners, chain sliders and the cam gear I like to tie a piece of string to the chain as I just let it drop down into the front cover area that way when I go back together it is slightly easier to retrieve (its not terrible either way). Again so long as you have devised a way to hold the chains on the idler sprocket you have nothing to worry about, IF a chain moves a tooth or a couple on the idler sprocket its time to take all the timing components apart and start from scratch. I would suggest you get new tensioners, not because I see them fail alot (or ever really) but they will come preset with a grenade pin in them so all you have to do is bolt em up and pull the pin when your ready. If you do get new ones and your timing is not right after pulling the pins practice compressing your OLD tensioner to get a grasp on what you need to do, it involves a pick down in a round opening holding back the ratchet mechanism and slowly compressing the tensioner in a vice until you can get the grenade pin back in. Also know its pretty common for chain sliders to be damaged, and or cracking, so inspect them while you have them out. I have found auto parts stores sell them individually, the dealership only sells a 4-600 dollar timing chain set to get new sliders (not sure customer cost those numbers were pulled out of my butt).
Unbolt your head bolts and pop the heads off... viola! easy right?
2005 Jeep Grand Cherokee - Gone but not forgotten!