I have a 330hp/350 crate motor in my 1985 truck, I installed a 625cfm Deamon carb a year ago. I recently noticed poor performance and upon ckecking for vacuum on the ported port of the carb I noticed it has little or no vacuum. I have verified the port to be open into the venturi and don't understand what may be going on or why I have no vacuum there.Any suggestions ? All help will be appreciated.
Thank you.

 

You're talking about the port that goes to the venturi? I believe that port only has vacuum at WOT. Try a port on the intake manifold or at the base of the carb, something between the intake valve and the throttle plate.

 

yea. don't use the ported port for that. thats for timed spark and it only pulls vacuum with throttle. Use a Manifold vacuum port.