I have developed a noise that sounds like an exhaust leak only when cold,when it is warmed up the noise goes away. I think it is a lifter noise but it does not sound consistant enough to be that. I am going to take the valve cover off and look closely. There was exhaust cam damage so I put a j-yard cam in this and ever since it has run funny and lost 2-3mpg Anybody have any thoughts Thanks
I intend to drive this car until something breaks then call a cab to get home and surrender the title to a junkyard but I don't want to be stupid about a minor repair

 

Confused. Location of lifters and majority of exhaust system.

First thing that comes to mind is that you had to change the exhaust cam already due to damage. So something must have been damaging it. Maybe the replacement cam you used was damaged in some way - a different way than the original. What was the cause of the damage?

 

Ecotec engines often break exhaust studs, leaving the manifold loose at the ends. I have successfully replaced the broken studs. The manifold warps a little bit over time breaking the studs.
My 460 powered motorhome has a broken stud and makes noise only when cold. When I run out of projects around the house I might repair the motorhome. Meanwhile I drive it the way it is.

 

the cam was replaced with a used one that measured the same everywhere but it obviously wasn't cause the car runs a little different but it's still good. I don't know all the proper names but here goes: one of the head saddles that anchors the cam was all gummied up so I drilled the oil passageway then line bored where all 5 cam saddles are to insure straightness. I saw another thread about the tensioner on the timing chain making noise so I am going to change that first and see if my noise changes. All I am sure of is the noise is in the back I cannot really determine if it is on the drivers side or passenger side but it does go away when I have driven about a mile or two and it does sound terrible to me when cold start

 

this is definitely a noise in the front cover as in one of those plastic parts or chain tensioner so I hope it does not break and it waits for another day