I can not tell if what i am hearing is the hedders or something under the valve covers on my 360 magnum? but i am leaning more twords the hedders, but just incase is there anything that can or needs to be re-adjusted under the valve covers? I accidently had my distributer installed 180 degrees out and i am hoping i didnt mess anything up by trying to start it that way. I had is on the compression stroke but accidently had it in 180 degrees out and whle i was cranking on it i didnt know it was 180 degrees out untill i heard a loud pop out the exhaust. But i know or a fact this is the first time that has ever happened to this engine so i cant imagine it getting messed up because its a low mile 360 magnum and that was the first oooops i have ever had with installing the distributer 180 degrees out. But the hedders on this engine are pretty old and i think maybe it's time for a new set and some new gaskets beause i am pretty sure i am hearing the hedders leak a little bit. But just incase thought id ask if there is anything under the valve covers the can be re-adjusted.