Hi, Trueslayer;
The EGR valve should be connected to "venturi phase" vacuum. This is sort of like spart port vacuum, but delayed and weaker. If you have the Holley/FoMoCo 1946 carb, this is the port that comes out of the driver's side of the carb. There should be a "spark delay" device after the port connection, which is a white-and-red cylinder with vacuum fittings coming out of both ends. One end says "To Carb" on it: connect that end to the carb. The other end of this "delay valve" should go to the center port of a WOT valve, which acts like a vacuum switch. This tee-shaped, round device connects into a manifold vacuum source (or the main vacuum canister, if you have one), with the other end going to the EGR valve.
The whole system should work like this (after the engine is warmed up, not before that): when the engine has reached at least 1/8 throttle, the 'venturi vacuum' starts. If you stomp on the gas, the 'venturi vacuum' phase goes away. The EGR should only be open during the 'venturi vacuum phase'. Trouble is, connecting straight from the 'venturi port' to the EGR valve does not let the EGR open, because the 'venturi vacuum' is too weak. That's what the WOT switch is for: it actually "switches" the EGR valve with manifold (or cannister) vacuum in response to the 'venturi vacuum' port. The Spark Delay valve prevents it from switching the EGR in too suddenly, which causes the engine to "fall on its face" if the EGR opens too early after idle.
Connecting EGR to Spark Port vacuum will work for emissions purposes, but it's really too much EGR, which adversely affects driveability. It doesn't need quite that much EGR. If you don't have venturi vacuum available, try connecting a Spark Delay valve (the red and white kind) AND a small orifice (called a 'vacuum restrictor') in series with the EGR valve. This will slow the opening of the valve and make it close earlier. This is how Dodge did it, but it does cause flat spots in the driveability.
