Is the EGR valve necissary?

[matchstick321]

Howdy, I'm new here so I'm not sure how to do this but here it goes.
I have a 1979 chevrolet k20 pick-up that my brother-in-law gave me.
It has a 350 engine with 4 barrel quadrajet carburetor and I got to looking in my owner shop manual and came across a page about the EGR valve I took a look at my engine to find that I did not have one...
I found that it had a plate bolted in where it where the valve was soposed to be.
I was wondering what exactly it did, if it uped the proformance of the engine or maybe even the fuel mileage, and if it would screw up my engine any not to have it.

[rcbildr]

From what I've read, it will not hurt performance. I can't remember exactly what it does...maybe someone else can help out with that. I just finished making a block off plate for my camaro.

[THE "10" SILVERADO]

the EGR is the exhaust gas recirculation valve, just a part of the smog equipment.

[matchstick321]

Well from what I've read it filters and cycles the unburnt gas from the exhaust back through the combustion chamber I'm just sorta wondering if that makes it burn less gas. Or if it is just another toxin filter like the catilatic converter.

[rcbildr]

If I understand what I read correctly it helps reduce emissions. By recirculating the exhaust gases it lowers combustion temperatures which reduces the production of NOx....or something like that. Some people have claimed their gas mileage improved by 1-2 mpg. I removed mine because I'm not sure it is actually working properly and almost all of the emission equipment on my camaro has already been removed. Fortunately, I don't have to worry about testing or inspections out where I live.

[matchstick321]

Haha Well It would appear that my truck has no emissions equipment I'm not quite sure what the laws are about that stuff where I live. Right now it does not have a transmission on it and cross pipe for the Y pipe on it was cutt off instead of unbolted to take the old tranny out and if you turn it on and look down through the floor pan and press in on the accelerator a little bit it will shoot about 6 inches thrust of flame out the pipe it's really cool to watch but as it is sitting in my garage it gets real clouded in there really fast.

[hatzie]

Originally Posted by rcbildr

If I understand what I read correctly it helps reduce emissions. By recirculating the exhaust gases it lowers combustion temperatures which reduces the production of NOx.

That's what it does. With modern computerized EGR and spark control it can be used to control detonation with higher compression ratios while running lower octane fuel.

Originally Posted by rcbildr

Some people have claimed their gas mileage improved by 1-2 mpg. I removed mine because I'm not sure it is actually working properly and almost all of the emission equipment on my camaro has already been removed. Fortunately, I don't have to worry about testing or inspections out where I live.

1-2mpg is a large gain...
I'm skeptical on making big gains like that by removing a properly working EGR. It's doubtful you would notice a mileage difference.
Broken EGR will screw up performance and cut into the fuel mileage big time so maybe they were blocking off a broken EGR system.

[matchstick321]

Well a friend of mine has a 90 chevy truck and his check engine light kept coming on so he pulled his codes and found out something was up with his EGR valve he checked it and the hose had been pulled off of it. He claims that he is getting better gas mileage now.
At this point I don't really care about mileage I have a 3cyl geo metro to drive when I want good mileage.

[cjlinkster]

Being that your truck is a 3/4 ton, it probably didn't come with an EGR valve. Trucks that had at least a 9600 # GVW were exempt from emissions during those years. I bet that your truck also has the c6p Heavy duty option.

[matchstick321]

Originally Posted by cjlinkster

Being that your truck is a 3/4 ton, it probably didn't come with an EGR valve. Trucks that had at least a 9600 # GVW were exempt from emissions during those years. I bet that your truck also has the c6p Heavy duty option.

The engine is not original. I believe it had a 400 in it before.