340 w/ 650 double pumper ?

I hear that Summit Racing is no longer selling Demon carbs anymore--too many bad ones. I think your Demon might be one of those bad units and Demon tech is just saying oh its too big. Not too say a 600 Demon won't give you better miliage--It might--but it still should not act up like that at those rpms. Heck Holley even sells DP carbs where both throttle plates open at the same time same amount.