[fordrodsteven]

Originally Posted by Freoway

Tricky doing accurate measurements, but I did use a rule across the tops of the rockers and eyeballed the travel of each rocker at the spring side. It all looks good. Cranking the engine over for about 20 seconds didn't wet any of the plugs on the right bank (where #8 is) but wet a couple on the left bank. Maybe there's a vacuum leak at the inlet manifold to the head right at cylinder #8? Hard to verify without removing the inlet manifold replacing the gasket, etc. Being in Australia, it'd probably take a week or more to get another gasket from the US.

This is what I do when I suspect a vacuum leak that is localized like your thinking; I put some water into a spray bottle and spray it around where I think it may be leaking. Usually if there is a leak the idle speed will change a little giving you a good idea of where the leak may be. Only time this didn't work for me was when my leak was on the valley side of the intake and it was leaking from the crankcase area (if you get what I'm trying to say).