Re: Vacuum

Posted by TxGoat On 2023/4/16 10:35:47

That sounds low to me for an engine idling in neutral. Is the gauge known to be accurate? Does the engine idle well and run well? Is the gauge connected to true manifold vacuum, and not a port on the carburetor? I'd expect a Packard 8 to run on the high side of the normal vacuum range, 20" plus or minus, at low idle of 300-400 RPM. Timing can affect vacuum, as can any engine loading, or extreme wear. An extremely worn engine would be an obvious oil burner. A stretched or slipped timing chain might cause low vacuum.