power valves tuning

If your car picked up e.t. by changing the power valve something is drastically wrong. The power valve is for low speed to part throttle cruising. At WOT it's always open, or at least it should be open. Only way it wouldn't be open at WOT is if somehow it has enough manifold vacuum to hold it closed.

Have you read the plugs or have a air/fuel ratio meter installed? I have to run 76's in the primaries on my mild 408 in a 750 carb. Seems like your 440 should want at least 76's as a minimum with an 850 carb. Be careful you don't jet it too lean and hurt the engine.