Ok I have 2 cars so double the problems. Please bear with me. Id also like to add that I AM checking my replies so please bear with me if I take I while. So I bought a 92 mustang month ago. Changed coolant becuase looked brown.(burped engine)Car has stock temp gauge so hard for me to understand because it says NORMAL. Out of nowhere the car shot up. I was already running around 230 temp so It overheated. I bought new motorcraft pump,balancer,timming cover and heres where I mightve got carried away. I took off timming cover and decided to change chain. It has a cloyes 9 key chain .I "THINK" I REALLY DO THINK THAT THE SMALL sprocket was on the 0 keyway. I installed a comp cams set at 0 keyway put eveything back together. So I added coolant with huge funnel(to burp and add coolant)and it wouldnt stop bubbling. I just thought man this thing has lots of air. So went for a drive and I noticed lack of power big time.I know it has a aftermarket cam (not sure what cam)I also head a accsinal "pop" sound that one i think is the chain hitting/rubbing so took everything apart was very exaushted yesterday thinking im repairing somthing and just A terrible day. So when do you know to install on a avdance key way or retared key way? I really suspect blown head gasket but I was thinking that scince I did the chain I must have installed the small sprocket differnet from original postion. Or can a blown head gasket cause a big loss of power!Were talking like 50 or more I mean when I punched it before i took it apart it hauled now its like a sluggish old stock cammer.