Customs vacuum reading

Is there a standard or range that the vacuum reading should be at idle. (about 800 rpm)

 

Talking stock, depends on elevation but 17-22 give or take ........................................

 

Here is a link. http://www.gregsengine.com/using-a-vacuum-gauge.html

 

17-22 inches is very good. 22 at idle, 17 when you bring rpm up. if you put a high lift cam in the engine you may have to add a mechanical vacuum pump to get power brakes working properly. remember, no vacuum, no brakes.

 

You mean, no power assist. Power brakes will still work with no vacuum, but there is no power assist to make them easier to apply, all power is manual (your leg).

 

sorry, NO POWER ASSIST.

 

800 RPM might be a little high for an accurate test. Is it a 6 or 8 cylinder? The number of faults and diagnostic tests that can be done with one is pretty amazing.

 

Make sure the gauge is connected to a source of full manifold vacuum and not to a ported or off-idle vacuum port.