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.
September 1st, is a better guideline date when considering planting grass seed. At that date, there is still ample time for the seed to germinate and live long enough to attain enough energy to withstand early frost. LIME, being added in any amount, if put down without a soil test, is taking a chance.