Replacing timing chain on 1991 auto DOHC (not the typical questions)...

[amolao]

Started yesterday, well I couldnt find any tips on things to watch out for, and the FSM is not clear enough. Yes I have done the chain on my SOHC manual trans. succesfully. Well the first thing:

How do you keep the cams from turning when taking the chain off??? I guess due to being an auto theres no way to make them stop. I used an impact tool. But when is time to tighten down, what should I do??

Also, after I go to TDC, distributor on cyl 1, top chain and cams align on the right spot and markings, how can I get the bottom chain on the right spots before I take it off and replaced with the new one?? Is not really visible until the take the top chain,etc off...should I just replaced it going by the same orientation before I get the new one on???

sorry about the long post and thanks