Vacum Guage ?

Hello I hooked up a small vacum guage to my intake manifold to ajust my carb. becouse I have a rought idle I can't get ride of. The vacum was about 15lbs. at idle 700rpm, but the gauge flutters about 2lbs is this bad . I hooked it up in back were the tranny vacum is same port.

75stringray 350/400 stock build except for Edelbrock intake and carb Q-Jet 1903 new,been thure all the normal stuff plugs wires cap rotor new intake gasket, carb gasket
Runs tops except for a rought idle ,but it will rocket off the line and runs very smooth no hesitation

so why the fluttering on the gauge problem ?
Rought Idle ?

Any Injput would be great TKS..........


|UPDATED|8/4/2003 6:59:16 PM|/UPDATED|

Is the flutter gradual up and down, or a sudden drop-off at regular ingervals? The latter indicates a misfiring cylinder or sticky valve. Does the RPM change with the vacuum drop? Joe

I know that manifold vacuum can vary if you have a valve that is not seating all the way. I would look to see if they variance has a pattern and time the pattern. It could be cylinder pressure leaking past the valve.

No serton time just flutters about 2 lbs does this at idle,also reved it up some and it seams to do it at about any rpm.?
I have tryed to different type of guages and they both do the same thing.

|UPDATED|8/5/2003 4:45:09 PM|/UPDATED|

15 lbs isnt enough. get it to between 19 and 21 and then see where you're at!!