I was tuning the 440/493 in the Charger and part of this includes checking idle vacuum to determine the proper size Power Valve for the Speed Demon 850 carburetor. I already have a 3.5 PV in the carb now. The motor is a '74 440 with a 4.15 stroke crank, 10.8 to one squeeze, Edelbrock heads and RPM intake. 2" TTI headers and the '509 Mopar cam.
Holleys website suggests to take a reading of the idle vacuum while IN GEAR and install a power valve with a number that is HALF of the vacuum. When I checked mine, I got a number of 7 inches of vacuum! Granted the engine wasnt fully warmed up. I pulled the choke plate some time ago since the car will idle dead cold even when its 40 degrees outside. It does idle better once it is warmed up, but my question is.......
Whats your combo and idle vacuum numbers? I never checked this on other cars before, so I dont know what to think. I'm going to take another reading with the motor at operating temperature and I'm guessing that it will be a higher number than 7 inches. If not, I guess the PV is right as is.