i am converting a race engine to e85. it was dyno tuned on race gas, and the power valves were plugged, as it was "race". now it will see mainly street duties with minimal track time..i plan on the typical adding 30% to fuel, but where should i start with a power valve? 640ish roller cam ..
here is a dyno sheet thanks for reading/

I would start by either sending that carb to a good E85 carb builder or buy a kit with all the components needed to convert that carb to E 85 with complete modifying instructions.
I sent AJ at Bob George racing my Holley 1150 CFM Dominator carb. for switching it over to E85,it still works great five years later
One of the local racers bought a kit to switch one of his 4150 Crabs to E85, it took some testing and parts switching due to our altitude here in central Oregon, 2500 Ft.+ His carb works great now also

Agree with Cab, power valves don't flow fuel, the holes behind them do. Knowing how much to drill them out is a hit or miss thing. Do you have the step drills? Drill one step, check, drill anouther, check. Go to big, fill back in, start over. That's just one part, I'm sure the carb and fuel block needs enlarging throughout the entire fuel circuit for E85.
Those guys have worked out all the kinks so you just bolt it on and go, money well spent in the long run.

i should have clarified, i plan on using a conversion kit that has new metering blocks.. but since my PV are plugged, what size is a good start?

Normally PV open at the vacuum number marked on them, so when vacuum drops they open, mainly at full throttle. Who knows, the hole might be the right size now. Are you doing both front and back? You'll need a EGT sender for each head pipe to tell where you're at. I heard E85 takes about 30% more fuel so drill the hole 30% more (fuel flow not hole diameter) if the kit is any good it should tell that and get you in the ball park. I would think you'll have to work the idle circuits and air bleeds too. Give it a go (what I would do) if it doesn't work out, send to the big guys.

I would run it without the power valve first to see how it does and then, if needed, add the power valve circuit and jet the primary jets 6 to 8 Holley jet size down
The local racer who did his conversion says the richness of the primary without a power valve helps cool his car down coming down the return road
My carb. has a Quick Fuel power valve in the front and it doesn't cool down coming down the return road It doesn't have a good cooling system either

To start and the way holley suggest which I don't agree with regarding selection... Take idle vacuum and cut it in half. 10" of vacuum, put a 5.5 in it to start.

That will get you a PV in the system to start with. Make sure you pull some jet out of the primary. Usually 6-10 sizes depending on the PV channel restrictor.

There is a better way to select this with an A/F metering and driving the car.

Total bs..........use cruising vacuum and keep the p/v below that according to how fast you want/need the enrichment.......I cruise at 12" and run a 6.5 and it works well for my combo............

use cruising vacuum and keep the p/v below that according to how fast you want/need the enrichment

This^^^