EGR; Good idea or not?

[omaha]

I'm putting together this motor for my 4x4 dodge with 318. The intake I have is a stock one with an EGR port. However, the thing is   kinda clogged with carbon (?).So... I am thinking of just blocking it off (also, it has this big round, pipe-threaded egr deal in the bottom of the plenum. It seems like this would affect airflow as it is directley below the primary venturi on one side, and it sticks up off the plenum floor like at least 1/2 inch). Now, I have always heard that EGR is actually somewhat beneficial if you are trying to squeeze every bit of MPG out of an engine, so I am wondering, how much MPG will I loose without the EGR. Would it actually benefit to keep it functioning? I know they can be somewhat problematic when they leak and can cause much rough running symptoms. Would like to hear some personal experiences of anyone who has kept track of fuel mileage or any other good or bad symptoms of removing it?
     Does the carb tuning change without it?  (I am assuming not)..THX .

[Cliff Ruggles]

EGR allows some inert matter to fill some space in the cylinder during the compression stroke.  Since it's hot exhaust gasses the idea was to help the engine burn a tad cleaner and emit less emissions.

They were only used at part throttle via a "late" timed port  (ported vacuum) in the carburetor.  If hooked to a strong ported source it will not work correctly.

I would not use the EGR at all, and fine tune the carb for best efficiency without it operational. 

No need to block it off, you might want to leave it open and do some testing with it at some point.  It's always fun to test those sort if things, if you have the time to do so.  I've always been able to get my engines to run fine without it, but almost always leave it operational on completely stock set-ups subject to emission standards/testing.

The big plugs in the intake aren't going to bother the little 318 much, I wouldn't worry about them.....Cliff

[Jim Elliott]

This is the "EGR" test on my motor home.

Climbing the hills out of the Coachella valley (Palm Springs) with the EGR connected my vacuum gauge dropped down to 6 inches which was the normal...
Blocking the vacuum line to the EGR the same hill dropped the vacuum down to 8 inches (more power).
On the flat and level my vacuum also increased by 2 inches and over time the fuel mileage also increased, Dumping (recirculating) spent exhaust gases will cut your power back and dragging a 18,000 pound motor home up & down the hills you know danged well every bit of power is needed....
(454 Itasca).

Jim

[Cliff Ruggles]

+1

Not surprised at all.  A heavy duty towing application is not going to respond well to any inert matter taking up space in the cylinder when it's in a heavily loaded environment.

One might see a very slight improvment in fuel economy at light load with a passenger car at steady freeway speeds.

My tuning has taught me that the N/A engines powering our cars and trucks operate in a wide variety of speed/load ranges.  This seldom makes adding EGR, or doing anything else that will reduce engine power, beneficial for the engine, or for your wallet, in the big scheme of things!.....Cliff

[omaha]

    Ok, thanks to all. I guess I will leave it unplugged and maybe experimant a bit later down the road.
I have shortened up the advance curve a little (idle at 12-13 and 34-35 at full advance). I am also using a vacuum canister from an old slant six applicatiol. (adds 13 to total). The old canister added 22! I assume this is to compensate for the egr.