Vaccum port ?

[Taylorman]

Is there any difference in taking a vaccum reading from the vaccum port on the carb vs the tapped hole in my intake on the back side just below the carb?

[roostwear]

If you're talking Holley, there are normally 2 vacuum ports.... in the base plate under the secondary bowl, and the port on the right of the primary metering block.Yes, there is a difference. The first will give you manifold vacuum, the second is ported vacuum.
I prefer to use the port under the bowl as opposed to a vacuum port on the manilfold as it typically is tapped into one intake runner.

[Taylorman]

Im talking manifold vaccum to tune idle mixture screw on my new carb with no vaccum ports(Dominator). All i have is a tapped hole in my intake below the carb mounting pad.

[Moneypitt]

Yes, that is a vacuum port and will work for that purpose..........MP

[Taylorman]

Thanks.