Long story short, I failed emissions with a high level of NOx, limit was 700 ppm (parts per million) and I'm up in the 3000 ppm lol. Reason being is the EGR system was not installed. Note that I have a holley carb, accel HEI distributor with vacuum advance and a different intake manifold to fit the carb some gm aluminum.

Why I need your help,

This is the one thing that I cant find a straight answer to because it may be specific to a 3rd gen engine. 305 with headers to be more precise. I'm wondering if the EGR's diaphragm will move by simply revving the engine is at at operational temperatures. I've found to many sites and tech articles that say yes and no. Yes because that is a normal operation, no because there is not enough negative back pressure and vacuum created just by reving the engine. One suggested creating the backpressure by plugging the exhaust with a socket, umm yea 2 1\1 3" socket? Dont have one I'll find something else. Anyway, I just need someone if they can check their car to see if this diaphragm moves or not. Careful not to burn yourself if you decide to do the favor, those parts do get hot.

Things that I've checked and done.
>installed a new aftermarket cat from autozone
>Installed the EGR ( junkyard part... )
> The Diaphragm moves freely by hand
>There are no deposits causing clogs
>Cannot check the solenoid as it is not there. Must have been tossed with the TBI to Carb swap. Though said somewhere, it will not allow vacuum to the EGR if there is a computer error code.
>Found that headers affect the EGR's operation as they relieve back pressure which the EGR uses to function.
>replaced old hoses with new ones
>cannot do vacuum tests as I do not have the pump
>Retarding the timing may lower the level of NOx, someone told me to advance it before getting the car tested. I would like not to believe that.

So all in all I belive I have the best hold on this that I can currently get. Cept for not knowing if I should see the Diaphragm moves or not. I would just like to know that its somewhat functional before I blow off another 30.00 on an emissions test. If it fails well, I hope they have a vacuum pump cause Im to cheap to buy one. Thanks for any help, I'll post an update if my efforts have proved worthy.

 

Where do you have the vacuum line connected going to the EGR valve?

 

Tried the carb and the vacuum port at the back of the intake manifold, infront of the distributor, nethier seem to move the valve. I was out there whatching the valve and holding the RPMs over at about 2500 to 3k but it still didnt move.

 

Ok I'm going to go up to the parts store and have them test the EGR with a vacuum guage. If i have this correct, with the engine off, and the vacuum guage hooked directly to the EGR it should hold 10" of vacuum, then when the engine is started the vacuum should release and the diaphragm should return to original position. I'm kinda hoping that this Negative backpressure EGR functions on the inside where you cannot see it. I should have tested that when it was off of the car. hmm..

http://www.autozone.com/servlet/UiBr...3d801c0032.jsp
pic from link abouve

 

Since you don't have the comp. controled solinoid for the EGR anymore, you have to resort back to the pre comp. era of EGR operation. I think the old way was ported vacuum from the carburator. That way the valve stayed shut during idle.

 

Yea, thats where its at right now. All the solenoid does is open and close the vacume for more fine tuned control. Though I would still like to know how much it moves when it does.