Where should you hook a vacuum gage on 2.8 L TBI Chevy?

On a 2.8L TBI Chevy engine, the best place to hook up a vacuum gauge is to the manifold vacuum port. This is typically a threaded port on the intake manifold itself. It's usually a smaller diameter port (often 1/8" NPT), and sometimes has a small rubber cap on it.

Important Considerations:

* Location Varies: While generally on the intake manifold, the exact location can vary slightly depending on the year and specific configuration of your engine. Consult a shop manual or a detailed diagram of your specific intake manifold to be certain.

* Avoid PCV Ports: Do not connect the vacuum gauge to the PCV (Positive Crankcase Ventilation) valve or its related hoses. The pressure in the PCV system is not representative of true manifold vacuum.

* T-Fitting: You might need a T-fitting to connect the vacuum gauge without disrupting other vacuum lines connected to the manifold. Make sure the fitting is the correct size and rated for the vacuum pressure.

* Accuracy: Ensure a tight connection to avoid leaks which will affect the accuracy of your vacuum readings.

If you can't readily identify the manifold vacuum port, a repair manual specific to your year and model Chevy will be invaluable in locating it. A visual inspection of the intake manifold with the air cleaner removed is also helpful.