This video is for adjusting the carb on a Techumseh Motor. The procedure is similar for most engines on two-stage snow blowers. Watch it and you should be able to adjust the carb on your particular machine.
Note: Some the newest snow blowers do not have carb adjustments. With today’s EPA requirements the manufactures are responsible for the pollution from their products and many have decided to limit how much you can change the fuel/air ratio on the carbs. If your particular carb does not have adjustment screws as shown in this video the only way to fix fuel related issues is to clean and or replace the carb.