What is the theory of the EGR system? On my 80 the EGR valve gets vacuume after the engine reaches operating temp. If the EGR valve is not working, is there any negative effects?

Hi Bernie!
The EGR system take a small amount of exhaust from the exhaust system and recirculates it into the intake for reburning. This inturn reduces the NOx (Nitrogen Oxides) levels. It also helps keep the cylinder heads a little cooler too. So at worst a inop. (stuck closed) EGR valve will raise your vehicle emissions and fail a sniffer test. If the valve was to stick open, the car may not even idle. Hope this explains things ok.
Sarge

While I don't know how to explain how the EGR works, I do know it's supposed to reduce emissions by recirculating unburnt fuel in the exhaust back into the combustion chambers to be completely burnt. If it's not working, it can affect negatively engine operation by reducing the engine vacuum, depending if the valve is stuck open or closed.

To me, all this tends to do once the car has any amount of miles on it, is to complicate the engine, its performance, create a number of potential vacuum leaks due to the extra parts and tubing.

If you're EGR is having a problem, I found the least expensive place to find a replacement was Pep Boys. It's made by Borg Warner and was cheaper than the resto houses and local jobbers.

I use my EGR valve to hold my magazines down on the shelf.

Thanks for the responses. I'm thinking that mine may be stuck open or partially open all the time. This may explain the idle issues and idle low vacuume issues I have been chasing for some time.

I pulled the EGR valve and there are lots of sooty deposits in the intake section. I'm not planning on pulling the intake anytime this winter, so, I guess the deposits will have to stay as is for now. I need to re-check to see if the vacuum signal is good to the valve.

I think Bill finally found a use for the ERG valve "Hold down magizines on his work bench"
Good One!

Dave
Mr69vett

Right on,I am planning on pulling my intake off this winter,I've got low vacume and I'm sure the gaskets are cooked by now.I'm gonna send the manifold down to the local engine shop and get it blasted,and rebuild the old q,jet.when its all back together there will be no EGR valve on it,I am sure I have seen a blocker plate in one of the catalogs somewhere . then I can have my own magazine hold down.

What's an EGR??

Hi Suzanne!
EGR is a emission system which came about in I believe was 1973. (Exhaust Gas Recirculation) On the carburated cars the EGR consisted of a valve, vacuum line, and a exhaust passage casted into the intake manifold. The valve is controlled by vacuum from the carburetor. It opens and closes according to the amount of vacuum being drawn at the carburetor.
If you look under the hood of your vette, look at the passenger side, under the air filter, next to the carb. you will see a round metal "thingy" with a vacuum line connected.... This is the EGR valve.
Hope this helps!
Sarge

A THINGY,! thats pretty high tech,