I was listening to the 1979 f150 idle when I seen a flicker. The rear head bolt on passenger side appeared to have a liquid bubbling at the base. I don't mean blowing bubbles. I mean there's liquid at base of bolt and approximately 1/4 inch around the bolt. It's right above header.

 

I may have dodged a bullet. I knew someone would ask me what kind of liquid. I just checked it. It's oil. I rubbed my finger along valve cover gasket an it was leaking. I tightened the rear bolt up. Couldn't believe how loose it was. Hopefully that solved it.

 

See... ya fixed it in 36 minutes!

Always troubleshoot before posting.