Pinging noise from engine

[col._kurtz]

Just finished changing head gaskets on a 97 ranger, 3.0 auto, 2wd. When it started up, it was making a loud pinging noise from engine. Sounds like metal on metal, no rhythm to it though, very random. Ran out of daylight before i could look and see if i missed something like a sensor plug or vacuum line. Any help would be greatly appreciated. Just pulled valve cover on side making noise, 2 rocker arms are a little loose with the studs tightened. I think its the exhaust on cylinder 4 and intake on 5, they are side by side. Is it normal for then to be loose??

 

[Haywire6000]

May be spark knock. The timing may be off. I would re check the timing just to make sure.

 

[col._kurtz]

Thanks for the advice but I found the problem. I pulled off the valve cover to check rockers, the push rod wasn't in the lifter. probably got knocked out when we were trying to get the rocker to go on. Luckily there was no damage to anything. Ever hear of that before or was it just my luck again?