Noisy PCV

[Mrbill426]

Fresh 340 engine with cam just broken in, and while I am trying to set timing and idle mixture etc I start hearing this annoying "chirping" sound.  I thought maybe WP bearing... nope... Alternator... nope... P/S pump... nope... belts... nope; I come to find it is the (brand new) PCV "rattling so fast at idle it chirps.  Is this normal; should it even be opening at idle?  When I crimp the hose it of course stops but the idle speed also drops by about 50rpm.  Bad valve, wrong valve, ignore it?
If has a bit of a cam (Lunati) but nothing radical.

Thanks

[PLY474]

Happened to me too specifically at higher advance / higher manifold vacuum.  I switched from the new PCV valve from Rock Auto (don't remember the brand / model) back to the old mopar PCV valve the car came with and it whistle went away.  Still using the old mopar unit. 

[Bullitt-]

  Not familiar with this issue so I made a search, turns out this is referred to as flutter.
This guy did his thesis on PCV valves.. It appears to be vacuum related
https://dspace.mit.edu/handle/1721.1/32895
"Overall familiarity with testing procedure for PCV valve EV-157 was
established. Through the testing of a few random valves, it became evident that a
flutter range existed around a vacuum level of 8 to 10 In. Hg. PCV valve "a"
experienced light vibration at relatively low vacuum, which prompted a series of
fast rises and falls in pressure in order to try and induce heavy vibration."

If there is anything out of the usual going on I would suspect that a vacuum leak may be the culprit.... I'd use a vacuum gouge to see if things look normal 

[Mrbill426]

Wow, that's deep.
I wonder if it's the cam... I'll have to check what the vacuum is at idle.  I wonder too if the factory PCV is spring loaded; the one I have is not... maybe that would make a difference.

  Not familiar with this issue so I made a search, turns out this is referred to as flutter.
This guy did his thesis on PCV valves.. It appears to be vacuum related
https://dspace.mit.edu/handle/1721.1/32895
"Overall familiarity with testing procedure for PCV valve EV-157 was
established. Through the testing of a few random valves, it became evident that a
flutter range existed around a vacuum level of 8 to 10 In. Hg. PCV valve "a"
experienced light vibration at relatively low vacuum, which prompted a series of
fast rises and falls in pressure in order to try and induce heavy vibration."

If there is anything out of the usual going on I would suspect that a vacuum leak may be the culprit.... I'd use a vacuum gouge to see if things look normal 

[Mrbill426]

Thanks!  Do you know if the old one is spring loaded?

Happened to me too specifically at higher advance / higher manifold vacuum.  I switched from the new PCV valve from Rock Auto (don't remember the brand / model) back to the old mopar PCV valve the car came with and it whistle went away.  Still using the old mopar unit.

[PLY474]

yes, spring loaded.  mopar p/n 3671076.

I wonder if the flutter is the natural frequency of the spring since there is no damper, similar to valve float??
I was getting the flutter/whistle at higher vacuum, like 15-18 in-hg (as I remember). 

[MoparLeo]

18" of vacuum is a normal reading at idle for a stock engine.