Hy Dave Douglas 56, I'm not at all familiar with that carb, but I'm wondering if that port connects to the power valve system, the same way that a similar port connects to the power valve system in the Rochester carb. With that port covered in a Rochester, the power valve is always open, because the valve is not connected to engine vacuum. Hence fuel mileage will be low and up here the vehicle will not pass an emissions test, hope that helps.
