What kind of vacuum to a 1966 389 ram air 4 engine-ported or manifold?

The 1966 Pontiac 389 Ram Air IV engine is designed to use manifold vacuum for its operation, particularly for the power brake booster and other components. Manifold vacuum provides a more consistent and higher vacuum signal compared to ported vacuum, which is typically used for carburetor operation in certain applications. If you're tuning or working with this engine, it's important to connect vacuum-operated accessories to the manifold vacuum for optimal performance.