OK, I'm a little confused. I assume that you're saying, you run on the center carb until reaching 80mph, and at that speed, the first and last start to kick in. But, depending on the tranny you have your rpms at 80 will vary. If for example, at 80 you're turning 3000 rpms, then it stands to reason, that any time you hit 3000rpms, the first and third carbs will begin to open. Thus, they open for hard excelleration when getting to 3000 rpm, right? How did you decide on 80 mph? I know that I very seldom if ever run that fast. Thanks so much for you patience.... kbyounger