1977 Other Toyota Models EGR valve

I have a 1977 toyota truck with a 20r engine. I am having trouble smoging it. The numbers are great it passes everything except they tell me the egr dont function. The way the guy checks it is with a vacuum pump. He pumps it up and listens for the idle to change. It dont. When I took the carb off to check the passages. They are clean. The vacuum that triggers it is hooked to venturi vacuum through a temp switch. I think this is correct. However
it also seems to route the exaust gas through the venturi above the throttle plate. Is this the correct way. The tube from the passage in the head for the exuaust connects to venturi vacuum above the throttle plate. I have been to the wrecking yards and this seems to be the case in the engines I find there. If this is the correct way for this engine then why does he keep listening for a change in idle speed venturi vacuum is not active in the idle circuit is it? It seems to me that this engine is different than others at least in the way the egr is routed am I nuts or what. I have tried and paid five times and failed the smog test each time. Due to egr not functioning.
it opens fine. It is clean. It holds a vacuum when applied. The ports in the head are open. The plastic plate right above the throttle plate has a Large tube that leads to the primary venturi just above the throttle plate and it seems that this is how it is supposed to be. Is he testing it wrong. Do you get what I am trying to say I think that there is little or no vacuum at venturi at idle I also know most if not all other engines I have worked on use manifold vacuum. Is this engine different or what I Cannot even find a place where I could hook it to the manifold. 22r engines seem to hook right into the manofold. Is this old 20r different.