At idle I take a reading....I get between -16 and 17 psi. The needle will flutter betwen 16 and 17 consistently.

Should the reading stay rock solid, or is this an indication of something amiss? In the manual, the fluttering needle is somethat described and it's indicative of a week valve spring? Or, actually could it be a bad (going bad) hyd lifter?

...that would be -16 to 17" ... (NOT psi...duh!!!)...

First guess: Idle mixture screws need to be adjusted.

What RPM is this happening at? Auto trans in gear, manual in neutral???

How does the car run? Are you troubleshooting a problem and finding a vacuum problem? I would think that the Edelbrock cam you are using would be the cause of some minor vacuum fluctutaions. I personally wouldn't be too concerned. As a matter of fact I'd be happy you are getting that much vacuum out of that cam, most people I've talked to get 12-13 inches!

Yes the needle should be steady.Any number of things could cause a 1 in fluctuation in manifold vacuum.

The 2102 cam , while seemingly long on seat timing should pull 17 in of vac in gear.I have never seen one that didnt pull that much vac..at least on clean running 350's... on a co workers short rod 383 he pulled 21 in of vac in gear with that cam.

Could just be needing some fine tuneing to clean it up.

Thanks guys for the replies.

I am actually trying to get to the root of a vibration problem (slight annoyance) in the engine. See my recent post on harmonic damper. I swapped out the damper yesterday, still have the vibe. http://www.chevelles.com/forums/showthread.php?t=93575

The reason for the vacuuum check was that another TC'r had a similar vibration problem, and after swapping out a myriad of parts as many of us attempt....pulleys, belts, dampers, ...he found out he had a weak lifter after running a vacuum check. Swapped out the lifter(s) and vibe went away. Something about the lifter leaking down and not be able to keep up with the engine.

The car runs fairly strong as a warmed over 350...4 speed M20. Just swapped out my Edelbrock 1405 for the Holley 4150 with adjustable spring kit and sec metering plate. What a difference in overall performance! The plugs have all cleaned up now...no more wetting, black or sooty. The install instructions states I shoudn't IN BIG CAPITAL LETTERS have to adjust the idle mixture screws....so I left them alone. Maybe they need a tweak or two?

I I recall, if I increase the RPM's, the flutter will go away and the needle stays steady.