On my stock 68'442 i'm looking to find out what the normal vac. should be at idle (700 RPM) from the front port (Rodchester) that feeds the Ported Vacuum Switch?

This Ported Vacuum Switch uses vac from the carb when it's cold and then switches to the manifold vac when it's hot? (FEEDING the DIST.)

It just seems that I don't have enough vac. when it's cold. Thanks for anyones help.

Dan

 

At idle, ported vac is near zero. The whole purpose of ported vacuum is that the port in the carb throat is above the throttle plate at idle (thus seeing near atmospheric pressure) and is uncovered at slightly off idle. Open the throttle slightly and you'll see the ported vac level increase.