One of the issues with PV timing (well two actually) is that some carbs are so rich that changing PV timing doesn’t affect anything. It is so rich that bringing it in later won’t make a difference.
The other is the opposite. You are lean enough that opening the PV sooner still doesn’t add enough fuel to make a difference.
The way I do it (and there are other ways but I’m pretty old and lazy) is I block the power valve off. Then I drive the car at a cruise so I’m on the main jet. Then I start taking main jet out of it until I get a slight lean surge at cruise. The I go up two sizes on the primary main jet and leave it alone.
Now you can put the power valve back in. Then I disconnect the secondary throttle blades and I wire them shut so they can’t open.
The I go out and mash on it real hard and I start looking at the plugs. If it’s lean, I open up the power valve channel restricters.003-.004 and go test it again. I keep opening up the PVCR’s until it’s correct at WOT.
Of course, of you are fat at WOT, then you would close up the PVCR’s a few thou until it’s cleaned up.
Then you can hook up the secondaries and test for WOT. Only change the secondary main jet to correct any issues you have.
Once you get the cruise right, you’ll find out how important it is to get the power valve open on time. The later you open it, the bigger the hole in the fuel curve you have to fill with accelerator pump shot.
It takes time to do it, but IMO it’s worth doing because the carb will reward you with incredible performance and drivability.
