myko

Sorry, that is what I meant. Picked that term up on another thread and tried to spread the ignorance.
Anyway, I have searched for spacers everywhere. I can find them for Corvettes but only listed up to fit in vettes up to '79. Is there some difference, other than those that differ in diameter, that would cause them to not fit all the C3 stock exhaust manifolds?

427Hotrod

The pinging will usually happen under those light throttle and *tip in* conditions. Since the original calibration of the timing curve included the EGR adding exhaust to dilute the mixture and lower cylinder temps...when we remove the EGR the cylinder will get a lot more full of good stuff that will actually burn and make power. In some cases the cylinder pressure gets a little high and you can get a ping. Not always though...those engines had such low compression they can usually do OK...just wanted to point it out in case it happened no one would freak out. If it does, we just recurve the distributor, or play with vacuum advance as needed. Usually more initial timing with less vacuum advance really wakes these engines up.

On the exhaust control valve..if you don't necessarily want headers and want to just remove the valve action, you can gut the flapper out of it and just use it as a spacer.

JIM

VetteV8

Or you leave it in position, and lock it in the fully open position; remove the vac.line and or the control rod.
Cor

myko

I thought about that. There are no emissions laws here so I am not as worried about that but when you remove the control rod there is a hole in the side. It might be as big of pain to try to fill that without worries about leaks as to buy a new spacer? The vac line isn't in place so it is wide open all the time. B/c I am not installing headers right now, I thought this might be one way to increase exhaust efficiency.

VetteV8

Not the shaft!!
the rod between the lever on the shaft and the vac. cylinder
Cor

myko

That makes a lot more sense. I wonder how much this would increase flow? It seems like I really just need to get headers ASAP.

Another question on the topic.
I realize the purpose of the EGR is to decrease NO in the exhaust by recirculating exhaust into the intake. How does this affect gas mileage and fuel efficiency? It dilutes the mix so it can't help gas mileage unless the exhaust will still burn with some addition of power. I know that it doesn't affect power at WOT b/c the vacuum is lost and the valve is open but how does it affect mileage at highway/cruise speed?

427Hotrod

EGR does not help fuel mileage at all. It takes up space in the cylinder that could be filled with a strong fuel mixture that will burn and push the piston down...even at part throttle.

JIM

myko

Right, so you have to keep the throttle down a little more to keep the same power being generated. I was just curious if you end up mixing more, less, or the same fuel with the exhaust to run at a steady speed. I was hoping for a real world example of someone who monitored gas mileage before and after removal? Or even a study from a tech school?

81pilot

Its not rocket science. Exhaust gases don't burn very easy since they are low in oxygen. The fact that they take up space that could be used for the good stuff makes the case that with out the gasses the mix is better. A better mix is more efficient. An engine that gets a good tune up gains power and mileage, same theory here. There is a line where to increase HP you sacrifice MPG, but in this small case you increase volumetric efficiency with the mixture and increase both power and MPG, but neither by a substantial amount.

thegazman

Have you ever tried to get an engine to idle with an EGR valve stuck in the wide open position?

Ganey

You have that out of context, VetteV8 was talking about the valve in the exhaust manifold for EFE & was correct.

VetteV8

Thanks!

Cor

bigjoepos

Resurrecting this old and good thread with question to those in the know.

When idling at operating temp is the EGR valve open or closed? At these same conditions is there a vacuum draw from the carb or only at higher RPMs.

After 20 yrs my 1976 can't seem to pass the NJ hydrocarbon emission test out of the blue.

Checking out all the normal culprits.


Thanks

Strokemyaxe

I have additional questions to validate resurrection.

I read everyone saying, "you have to block the EGR with a plate". What plate? Who makes this? How do I get one?

Thanks!

jb78L-82

I love the tree huggers who calim that an EGR valve is good for combustion, cools the incoming mixture, doesn't effect mileage, and certainly has no effect on power production....yea right....Its common sense and basics physics, both of which are often lacking often.

jb78L-82

I love the tree huggers who calim that an EGR valve is good for combustion, cools the incoming mixture, doesn't effect mileage, and certainly has no effect on power production....yea right....Its common sense and basics physics, both of which are often lacking. Get rid of the EGR valve unless you must have it for emissions inspection...then block it.

PcolaPaul

Available at most Auto-parts stores and from Summit or Jegs. About $10 bucks,

Wibäck

So if I replaced the EGR with such a plate would that in any way affect the choke tube next to it? I mean will it change the behavior of the choke during warm-up (1975 L48)?

Thanks
Fredrik

dugsgms74

Actually, while the EGR does not cool the intake charge it significantly cools the combustion temperature, leading to lower NOx emissions and tendency for detonation. Also, the EGR does increase mileage by reducing intake manifold vacuum and therefore suction throttling loss. And since it doesnt work under load, it has no effect on power when it matters.

The EGR valve is truthfully a great device. Think about it, that simple device allow your engine have variable displacement and a variable compression ratio, pretty impressive for such a simple, reliable device.

Once you start to understand how a EGR actually works you begin the realize that on a otherwise stock engine there is no reason to remove it.

thegazman

Opps, excuse me. I thought this post was about EGR valve operation and removal.