Full manifold vaccum at distibutor

My 1985 G20 van with 305 has full manifold vacuum at the distributor at idlePretty sure it is alll connected up right. Vacuum source is the base of
the carb. Vacuum is high there too but I am not sure whether this is normal or not or where the line goes to after it leaves the carb. Any help would be appreciated.
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Any diagram on the under hood vacuum hose tag?

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Yes, but I cant tell what a lot of the stuff is. Best I can tell it is hosed right. I recently changes all the vacuum lines but it had the same problem before I did that. Next time I get a couple of days open I am going through all the hoses again. Could anything be broke that would cause this.

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Well, full vacuum advance at idle is the most efficient set-up, emission requirements notwithstanding. Maybe your G20 had the HD emission package. Is it causing any problems??
Regards, Al.
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Some GM cars have a temperature actuated vacuum switch to apply full vacuum to the advance diaphragm when the engine is hot. Raises the idle to cool the engine down. Can't say about this van. Chilton's has vacuum diagram books.
Al
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