Paul L

My new Edelbrock carb arrived today and I have a choice of timed or full vacuum for the distributor advance. The pic shows the current Holley setup. What do I have at the moment?

Larry B.

It looks like you have full (manifold vacuum) If there is vacuum at the port at idle then you have manifold vaccuum. Ported vacuum build as air velocity increases manifold vacuum is below the throttle plate... ported vacuum is above the throttle plate.


[Modified by Larry B., 2:04 PM 6/24/2004]

LB66383

It looks like you're coming off manifold vacuum. The easiest way to tell is to pull the line off the vacuum advance with the engine idling. If you hear a sucking sound when you put the line near your ear, and can feel suction with the end of your finger, and the idle speed gets slower, it's manifold vacuum.

Paul L

Thanks fellows. I did the test. It's full (manifold) vacuum.