I bought a vacuum guage tester a couple days ago and was curious...where/which vacuum line do i connect it to for most accurate readings? if someone could supply a picture of a line etc it would be greatly appreciated. thanks guys

 

any vaccum line that goes to the manifold will do, like the vaccum tree on the firewall

 

i usually take off the Line on the Vaccum tree that says A/C

or the one to the left of it that is capped...

 

it depends on the car if its a injected it doesnt matter, if its carbed you would want to make sure you take it from a port below the throttle plates.