Carter 750 float level

From memory the 9755s is a Federal Mogul Carter carb and used the short primary booster from the 625 Carter. Because the booster is shorter it wont receive the same vacuum signal and so it will achieve primary booster flow later. If you raise the float level it places the fuel level closer to the booster outlet helping it begin quicker.

Also if you go through the Carter literature you will find that they state different float heights for different needle and seat sizes. The larger the size the lower the float level.