Size of Car Vacuum Gauges

There are many car vacuum gauge sizes to choose from. For example, the Equus 3620 is 12 inches high, 1.50 inches wide and 5 inches long. It has a weight of 11.20 ounces. But other units will not have the same measurements.


This device is used to monitor the vacuum of the engine. Using the vacuum gauge, a lot of information about the engine can be attained. With a proper understanding of the gauge, the spark timing can be adjusted. The fuel settings can also be tuned up. The gauge can also display the pressure in the intake manifold of the engine.

The Gauge and the Engine

The engine works like an air pump. Inside the cylinder, the pistons move up and down. The pistons go down on the engine stroke, drawing air in the system. What the gauge does is show any air leak or loss. The point where the loss emerges with regards to the piston determines what the problem is.

No matter what the car vacuum gauge sizes are, it will show a steady reading if the engine is properly tuned. If you step on the pedal, the vacuum level goes down but eventually returns to a consistent reading.

The vacuum will show variations if the ignition system is in poor condition. A poor system will have the needle vary by a couple of inches along the dial.

How to Assess the Readings

If the vacuum reading is unsteady, it could be a sign of damaged spark plugs. It may also signify a bad coil or damaged plug wires. The gauge is essential because these problems can be hard to see. Once these problems manifest, you should test or replace those parts.

If the gauge reading is fluctuating by 3 to 5 inches (7.5 to 12.5 cm), it means the exhaust valves are not working correctly. This may indicate a problem like a defective cam lobe, weak valve spring or defective valve stem. Sticking valves can derive power from the engine.

Other Information

If the reading goes up and down rapidly, there is a problem with the blown head gasket. If the gauge does not rise when revving up, there is too much exhaust back pressure.

There are many car vacuum gauge sizes available. However, the physical dimensions are not as critical as the diagnostic features. Study the device first before using it so you don’t make mistakes when reading.

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