454Mag, I cruise normally around 35 MPH. Slow I know, but I don't need to get anywhere in a hurry.

That's exactly what I do. Try to keep above 5" on the vacuum gage (4.5 PVs) which is 3200rpm at about 50mph. Of course that gage is more fun when it reads on the other side of zero.

Blue,
just go to 3.5 PV...you should still be plenty rich...more fun!
Ben

Oh things to ponder BP, the carbs are on the bench )

I can't stay on a nice plane under 40-42mph @ 3400. Very happy at 38-4k at 55-60mph. WFO 5k at 80mph last year and looking for a lil more this year

Blue,
I tried some 2.5 PV's but they would open to late for comfort. One thing I did learn testing with an AFR gauge, is that the Holley carb is pretty amazing. From 3500-5500 RPM (this was I fast as I was willing to stare at the gauge vs driving the boat) the jets alone would hold the AFR at 13.6-13.5 at all RPM's...how does it know? These carbs are as smart as my cell phone...
When he PV's open, the AFR drops to 12.2 12.4. This is some richer than I would target, but I guess the way to lean it some would be with larger high speed air bleeds. You can figure this out and then give me some good direction.

You must be n/a Ben, that would be way lean for me. I set my carbs up fat and for the PV to switch early to avoid that lean spot just before they open. I use the LM2 and see the same thing when the PV open. The real fun though is WOT a/f readings