I have a 71 dodge dart with a 225 slant six. I have rebuilt it, installed a comp cam, milled the head .050, valve job, 4bbl intake, and a Holley 390 carb. My question is what is the best power valve for a daily driver (40 miles interstate a day). I installed a 8.5, the old one didn't have a number on it. I was just wondering what other people think. Im running #46 main jets. I live in Colorado at 7,200 feet.

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67' Dart GT Convertible; the old Chrysler Corp.
82' LeBaron Convertible; the new Chrysler Corp
07' 300 C AWD; Now by Fiat, the old new Chrysler LLC

the Holley site is OK, but is more for the V-8 guy and doesn't take into account the six can run high vacc on the street then quickly dip to 6" on part throttle passing a truck, it also is not as accurate for people running a heavy vehicle with the smaller engine ... Most folks tend to run a 10.5 PV, but with your altitude may be more in the 9.5/8.5 range...that being said....I have successfully run dual stage PV's in the Hpak duster for street use (12.5/6.5) since I only needed partial enrichment in the car not a bucket of fuel on passing (i would swap to a 10.5 at the track, then swap back).

How is your in gear vacc. reading at highway speed? and how far does it dip when you get on it to pass a semi?

-D.Idiot