Losing fuel pressure on new setup

Well i swapped carbs to a 600? Cfm holley i had laying around. Dont know much about it other than its old and worked the last time i used it. The car ran without a hitch with the other carb so im going to throw a kit in my good carb and reset the float levels. The weird thing is my pressure still did the same thing. Went from 7 to 2. It seemed to take longer but it still dropped.

Any chance its a faulty gauge? The car ran and drove for 30 min without a problem

My next plan is to put the good pump and reg back on with this carb and see what the pressure does and how it runs. I will also add clamps on my rubber connections as suggested to be safe and see If it changes anything

I think you found your problem.

You said in your first post that the motor starved and died, but now its not? So whatever you changed made some sort of difference.

I would leave everything as is. Start car and drive it, drive hard, drive it normal, etc. If it doesn't die or sputter, pull over and check the fuel pressure. If it is low, I would suspect a faulty gauge.