If I eliminate the EGR value with a blocking plate on the intake manifold, do I have to also block the port in the head?

Thanks Tim

 

No. Blocking the plate will help cool intake off some, but otherwise no difference. Pay attention to timing curve so you don't get detonation with it removed.

JIM

 

Wait..........I always thought the EGR valve connects the exhaust crossover with the intake tract.

If so, removing the EGR and only placing a block-off plate means that the intake will function like having the EGR open all the time.........someone please correct me if I'm wrong.

I'm convinced the EGR and carb chokes were designed by Satan! I always buy a non-EGR performer intake without a heat-cross over.

 

EGR is an emission device that's good to use if it's there. The benefits for using it far outweigh the bennies of removing it.

 

Thats what I'm afraid of and why I asked the question. I don't think having the port open all the time is good. Maybe switching to a new manifold without EGR is a better solution. I'm not sure exactly how the EGR system is configured. Where does the exhaust come from that is entering the manifold?

 

The exhaust comes through the exhaust cross over ports in the center of the heads. If you were to remove the intake you would see a hole on each head between the 2 sets of intake ports that makes a direct connection to the 2 center exhaust ports inside the head. This passage is normally used to warm the intake during cold starts. There is a *heat riser* valve on one of the exhaust manifold outlets that somewhat closes during cold starts to force exhaust through that passageway and on out the opposite manifold. The intake manifold has a cast in passageway that connects the right end left side *exhaust crossover* ports in the heads.

On EGR manifolds that passageway is also cast to bring exhaust to the EGR mounting pad. If you remove it you will see two ports. One will have exhaust flowing out of it from the heads/crossover port and the other goes into the intake runner or plenum area that normally carries the air fuel mixture. There is a gasket that separates the two ports at the EGR. You could have a leaking gasket under the EGR that can cause a vacuum leak or an exhaust leak depending on where it's leaking. The EGR valve opens and allows exhaust to pass through it into the intake plenum/runners. When closed it seals the two passages off. When removing it, must folks install a flat plate to cover both passages and use the stock gasket. This prevents leaks and passage of exhaust into the intake runners/plenum.

The EGR *cools* the combustion event somewhat and reduces detonation as well as helping NOx. Seems strange to say exhaust *cools* anything, but what it really does is take up space that would normally be filled with a clean air/fuel mixture. Since the exhaust won't burn again, there is less good fuel/air mixture in the cylinder to ignite...thus less pressure to push the piston down. High cylinder temps increase NOx so this cools it down some to reduce it. The EGR is disabled at WOT if it's working right and typically only operates at light throttle applications.

This is why I said to watch timing and pinging because with it gone, the cylinder pressure will increase because you have more air/fuel in it. That makes a faster burning cylinder and the timing curve needs to be good.

Hopefully this helps.

JIM

 

The primary purpose of the EGR valve is to "reburn" exhaust gas that would otherwise enter the exhaust system and then out the tail pipe with more pollutants in the exhaust mixture primarily NOX. The EGR valve dilutes the relatively pure air that would be entering the combustion chamber and is the reason that many eliminate the EGR valve with blocking plates (cleaner combustion air='s ?). It is not a benign emissions control device-it's primary role is to reduce emissions and there is a price for that role. On an OEM 70's engine, it will effect performance and not positively. Late model cars are a different story since they are designed with the whole emissions package in mind, unlike the older engines where all kinds of emissions hardware were slapped on these engines with the primary goal to meet the new emissions standards that were coming on line at the time. Most folks I know, would never intentionally build an engine with an EGR valve or leave the EGR valve on an OEM 70's engine unless they have to meet an emissions standard! On my 78 L-82 eliminating the EGR valve definitely improved the idle characteristics of the engine and there were zero issues with detonation or the timing. The car ran better and felt more responsive after the EGR removal-I could advance the timing with no detonation) Just to be clear!

 

Thanks guys, for all the good information. Jim, your description was exactly what I needed to hear. Thanks for explaining it so throughly.
I think I'll try the blocking plate and see what happens. Thanks again to everyone who replied......Tim

 

excellent information. Tim let us know how it goes with the EGR Valve removal, are you still using the CCC in you car?

 

Larryg3,
Yes, I still have the CCC hooked up, Personally I like it and plan to keep using it. I am planing on a rebuild this winter, nothing special just freshen up the motor. So it might be awhile before I have any results. The car runs very well now but has over 150k on the engine and drive train. With that said, it does idle a little rough but pulls 18 hg of vacuum at idle, so I don't think I'm going to find too much wear internally. I'm doing the rebuild basically for piece of mind....Tim

 

Dumb Question Time !!!
Does removing/blocking EGR effect the choke (heat operated one) ???
My EGR doesn't hold vacuum so I'm assuming-it's shot ('74 L-82 4speed),
I've disconnected the vac line to it but left it in place- so is it OK to do this ?????
According to my research my EGR came from a '70s Camaro
(by the serial No. on it) and the only replacement with the same serial No. was over $150US.
Any help greatly appreciated.
Thanks from Downunder (Australia).
CHEERS
GAV

 

Yes, it's Ok to leave it unhooked as long as the valve is not allowing exhaust to pass through it internally which I doubt it is since it seems to be running fine. If it was leaking you would have a rough idle. Removing it does nothing to change choke operation.

JIM

 

Tim81, i am also planning on a rebuild of mine, it runs great and only have 68K but it is time to change the gaskets as i have oil leaks and the trans needs a rebuild (also leaks from the pump gasket) so just figured might as well one of those since i am there might as well.... moments. i plan on changing heads for some dart iron eagles and a 268H cam. but i do plan on keeping the CCC.

 

Remove the EGR for a cleaner look and also for a cooler intake air. EGR system adds heats to the engine and also carbon deposit to the intake. EGR eliminator will work in most 1986-95 fords which uses light gray EGR.

 

All good information here - just a note that the EGR is vacuum-operated...so during WOT and other high-throttle operations it has zero impact on performance.

 

Thanks for bringing this useful topic back to the top!
I have not read such a concise clarification as given by Jim in #6

Only one question about the knocking: If the standard timing curve still is in operation, why should knocking become an issue? After all, the EGR operates That being the case, why then knocking? That does not happen at light loads? Or?

Also a nice explanation about the 'stream of exhaust gases through the inlet manifold casting, heating up the intake, by partially shutting off one of the exhaust pipes by means of the heat riser.
Cor

 

Fords? Does it help to know which Ford they fit? Just askin.....

 

I just removed mine. The valve would still hold vacuum but did not seal against exhaust gases anymore. This means I always had some flow of exhaust under the manifold.

The EGR Vacuum Control Switch had been broken/disabled by a previous owner already.

It does clean up that side of the manifold. I am hoping it will help with hot restarts in the summer.

 

The EGR valve below my exhaust manifold is still there despite the fact that the rest of the emissions equipment was removed by the PO. I am installing a new motor with the stock exhaust (for now) and would like to remove the short piece with the valve.

Is there an aftermarket header collector that will fill this gap with stock exhaust manifolds without needing modification?
Are there hugger headers that will allow the EGR piece to be removed and fit to the stock exhaust pipe locations (I have vortec heads and A/C). I know that the Hooker huggers won't fit with side motor mounts but how about others?

Edit: The valve piece is 1" long with an additional 3/8" of reducing length. It is 2 1/8" in diameter (with reduction to 1 7/8" inner diameter at the end of the nipple).

 

Thats not an EGR Valve. Its a heat riser valve. and yes they sell a spacer to remove it.