When using the single-vacuum distributor, the vacuum hose runs from the vacuum port on the left side of the carburetor to the vacuum canister on the distributor. In that case, the vacuum port on the rear of the carburetor must be plugged.
For most cool season grasses and for folks living in northern climates, the best time to plant grass is in late August, early September. Depending on exactly the climate you have and the type of grass seed you're planting.
Spring Grass Planting. An early spring seeding, during the month of April (or March if the snow has melted in your area) is another good option. If you plant early enough, you'll give your tender young grass enough time to establish it's roots before the heat of summer arrives.