The correct way to adjust a Rochester Monojet carburetor on a classic Chevrolet inline six: the procedure is simple but the sequence matters.

Start with the idle mixture screws — typically two screws for a Monojet, though early units had one. Back them out two full turns from lightly seated as a starting point. Warm the engine to operating temperature. Adjust mixture screws for peak idle vacuum. The vacuum gauge is more reliable than a tachometer for this adjustment.

After idle mixture, set the idle speed to the factory specification. Recheck mixture screws after setting speed — idle speed affects the mixture circuit. The final step: verify the choke operation. A sticking choke is responsible for more cold-start problems on Rochester-equipped cars than any other single issue.