No doubt calibrating the gauge is a good thing. I use an aquarium manifold to connect my gauges to a common vacuum source either a vacuum pump or a single intake runner. This way I can set all the dampers for equal needle positions.
But a lazy needle can be the result of a restriction in the test tubing path or port tap, as well as a faulty gauge. Had a spider camp out in a tube once.
Therefore, swap all the bits between the carb throat runner as well as the gauge to eliminate any possibility of apparatus faults.
You don't want to "fix" an engine because of a test setup problem. You want to know for sure that a vacuum issue truly exists in the runner.
I've been bitten by test equipment faults in many aspects of trouble shooting. So when the eyebrow goes up, and "what the..." comes out of your mouth, make sure your database for problem solving is accurate.
You have to ask yourself, what can cause weak intake pulses? Unfortunately, most answers involve some sort of mechanical issue, if it isn't a false reading.
One more thing. All your new parts aren't new anymore, after they've been put into service. Sometimes they have very short expiration dates due to unseen influences.
I once ruined a brand new rebuilt V8 engine because the cam bearings were installed wrong. Oil starvation doesn't take very long to muck up an engine, new or old. The thing ate itself up with zero miles on it, because I didn't believe the only oil pressure gauge I had (a used one) was working (the needle never budged and I couldn't bleed the pressure tube).
Early hard lesson$.
