measuring vacuum on a 4.2L motor

[deadboy1977]

Vacuum on my motor jumps from 12-14 as motor runs from what I remember - have not checked it lately tho. Gauge was jumpy between 12-14 as I remember. I do need to check this again! This would seem to be a minor vacuum leak???? Question is how do I find it if I have one???? I am trying to remember where I put the vac gauge when I did the test??? Somewhere on the plenum I remember. WHERE should I put it?? What would/should the vacuum be for a 4.2L with 155000 on it?

[roverandom]

Huh ? not sure I understand your post. Are you trying to find a vac leak? try inspecting all vac lines, if you think you have found a "bad" hose or gasket ( with the engine running) spray some brake cleaner (carefully) or WD40,engine degreaser etc at the suspected area. If the engine runs like shit, hey presto, you found the leak ! That is the easy, low buck test. Hope this helps.