question about ignition and cam timing

I went to set my timing yesterday and with the spout in the pointer kept jumping around making it practically impossible to read what it was even at. with the spout out it didnt move around and i could set it easily. Any ideas on why this could be happening. I hooked up my test light to a battery outside my car for power, could that have something to do with it?

question 2, my stage 1 cam is advanced 2 degrees. Could advancing your cam cause you to pull less vac at idle cause im only pullin 12 inch of merc

thanks

Drew

Ok but i am pretty sure when i checked it before it didnt jump around a lot like it was doing yesterday...haha it would jump from 20 to 10 to 15 etc. thats normal?
im not saying you are wrong im just asking.