Idle creeps UP by itself...Vacumn leak???

[waterboy1976]

The title says it all.....I have amild 350 with a 650 mighty demon carb...bal and blueprinted engine.....544 lift cam 234/244 duration......when I warm her up and set the idle rpm at 850....it eventually creeps up and sets in around 1300......am I looking at a vacumn leak...or is this a carb adjustment issue?? where should I start....

 

[Tomcatt]

sounds like a vac leak