Been there done that. It's pretty intimidating digging into the OHC modular ford's. I'd rather wrench on a pushrod 5.0 anyday before touching a Modular ford, but once you do it, it's actually easier than some may think. Snap-On sells a cam retension tool that hold's the cam's in place while you remove the chain's. Used that before with a buddy, but the tool is pricey, so I dont have one of my own. A backyard trick that I use now is to align the the harmonic balancer notch at top dead center (TDC) on the timing cover before you remove it. Once it's off I use white out and mark 10'O clock(cam) to 6'O clock (crank) on the left bank cam sprocket and chains, and 3'O clock (cam) to 6'O clock on the right bank crank cam spocket and chains. With those mark's for youre reference, just make sure to keep the left/right chains seperated, all you have to do is connect the dot's litterally ! Same goes w/ the secondary chains an sprocket's, just align youre whiteout marks on the chain links, to your sprocket's and you'll B ok. Or just buy the cam retainer tool and have it for good, either way is full proof.
