Vacuum reading

[spinelll]

Does a vacuum reading have any relationship to head gasket health?
Other than a few blips I'm reading at 20. See attached.
At nearly full advanced.

 

[Y-Blockhead]

Does a vacuum reading have any relationship to head gasket health?
Other than a few blips I'm reading at 20. See attached.
At nearly full advanced.

Yes, a vacuum gauge is an excellent diagnostic tool. This may help you.

 

[mcgarrett]

If the needle reads steady at 18-22" it generally indicates your engine is pretty healthy.

 

[Bob Bidonde]

I have this vacuum gauge (on the right) in my Victoria. At idle and at a steady cruising speed on a level road, the needle stays in the yellow on the right.

 

[Y-Blockhead]

My vacuum gauge read 20-21 In/Hg at idle.

 

[mcgarrett]

Many of us can remember when some American cars came equipped with them from the factory. Those WERE the good old days!

 

[The Master Cylinder]

I have this vacuum gauge (on the right) in my Victoria. At idle and at a steady cruising speed on a level road, the needle stays in the yellow.

Looks like you have two yellows.

 

[old31]

I was wondering the same, which yellow?

 

[David in San Antonio]

I’m guessing the good yellow is the second yellow band. It’s labeled Deceleration, which would be high vacuum. That first yellow band is labeled Poor.
I think our A engines run relatively high vacuum at constant speed, perhaps because the carburetor, intake manifold, intake tract in the head, as a system is relatively restrictive.

 

[Bob Bidonde]

Yes, the good yellow on the right.