Needle shaky on FP guage

[MSDGN]

Was resetting my fuel pressure last night...I do have a KB hood mounted guage but hooked a guage to the fuel rail...with the vacuum line off the regulator everything is fine but when I put the vacuum line back on the needle on the FP gauge was shaky...not bouncing around...just shaking a little...not steady...checked my hood mounted gauge and it was steady...does this sound like a problem with the guage or something else?...

 

[The Radius Kid]

Nope.Sounds like the gauge is reacting to vacuum fluctuations in the manifold.What cam you got?

 

[MSDGN]

CC 206/206...

 

[The Radius Kid]

If the gauge is only fluctuating a little,I wouldn't worry about it.But if the gauge is fluctuating a few #'s or more,I'd be looking for a miss in the ignition or a bad cam lobe,basically anything that can cause a cylinder miss or two and the attendant vacuum fluctuations.