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.
Choose a grass seed that grows well in your area and plant in the spring or fall; avoid planting during the hottest part of the summer. Avoid using herbicides on the lawn before or immediately after planting. Once the grass is well established, choose a weed-control product that is specific for your grass variety.