I posted a while back about getting a 770 truck avenger carb. It had a off idle bog and I posted about it and got alot of good responses. Well the tech dept. at Holley said I needed a 670 on my mostly stock 454 (mild cam, edelbrock intake and dynomax headers). I got a 670 in and bolted it up. It ran good and seemed ok until about 3 days after I put it on and finally got a chance to really hammer on the truck. 2500 to 3500 it spit and sputterd and did not pull good. After 3500 rpm it pulled like a rocket. So I call Holley back and tech. says maybe something wrong with carb,we will send you another. Got it a week later and the same thing!!! So I just got off the phone with tech again and now the think maybe I need a 770 cfm on the 454??? So now I will try some of the original sugg. I got from my first post and see what happens. Rant off.