440 six pack high idle

I see some questionable advice. I would start by disconnecting the outboard rods just to make sure that the secondary carbs are closed completely during idle . Start the motor and check for any change.Also make sure that the primary carburetor butterfly is moving freely and not getting stuck partially open.but my number one concern would be that the outboard carburetor air idle is not adjusted properly which requires you to remove the outboard carburetors and check if the lead plugs have been removed at the front of the base of the carburetor. My guess is someone has open them up. Return to factory setting ,add a quarter to half of a turn more if you're running a hotter setup.