EGR
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Junior User
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EGR
I was thinking about getting rid of my EGR plate but then someone told me that with the lower quality of gas these days that the EGR system helped reduce detonation. Has anyone noticed a difference between with and without EGR?
MSEE
Joined: Apr 2004
Posts: 10,386
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From: Austin, TX
Don't remove EGR. Engines with EGR are calibrated to run leaner with a steeper timing curve then their non-EGR predecessors. If you remove EGR without compensating for it by rejetting the carburetor and recurving the distributor, you'll subject your engine's combustion chambers to heightened temperatures, which can lead to pinging and dieseling. It's not related to the quality of modern gasoline. If you remove the EGR system, you'll have to endure a lengthy trial-and-error tuning process that will at best get you to where you were in the first place.
There is no benefit to removing EGR. EGR works by displacing a portion of the air/fuel mix with inert exhaust gas that cannot be burned, which cools the combustion chamber temperature and reduces NOx emissions. It's not "smog junk"; anyone who tells you otherwise is heavily misinformed.
There is no benefit to removing EGR. EGR works by displacing a portion of the air/fuel mix with inert exhaust gas that cannot be burned, which cools the combustion chamber temperature and reduces NOx emissions. It's not "smog junk"; anyone who tells you otherwise is heavily misinformed.
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I found an older post with a diagram that showed my egr system and how all the vacuum hoses hook up. It has the 2 port vacuum switch in the thermostat housing. I never fooled with the engine when I bought it in 98'. The egr was never hooked up and it did run a little off. It has a 2 barrel 650 cfm Holly that I put on in place of the stock 2 barrel carb. I capped the auto choke hole in the manifold and it has a manual choke now. Other than the carb the engine is bone stock. Will have to see how it runs with the egr hooked back up since I never ran it with the egr on : ) It also has that vacuum delay thing you were all discussing in another thread. I happened to find it in my glove box and popped it on between the carb and the distributor.
MSEE
Joined: Apr 2004
Posts: 10,386
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From: Austin, TX
Remove the EGR valve (two bolts) and apply vacuum to the port. Make sure the spindle moves inward when vacuum is applied, and springs shut when vacuum is released. It's fairly easy to see it opening and closing by looking at the inner flange of the valve.
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I took the thing apart and it seems to work fine. So I went to advanced and ordered a ported vacuum switch as that's the only thing else that could be stuck open. It hasn't been used in several years and the one port was plugged so that all the vacuum could go to the distributor.
Hotshot
Joined: Mar 2007
Posts: 10,101
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From: Pa
Make shure the EGR plate is not clogged. Pull the plate off the manifold and make shure its not plugged up with crap restricting flow.(Mine was all carboned up) When I went to Napa to get an EGR gasket the guy wanted to argue with me telling me my 74' had no EGR.
Ended up getting an EGR gasket for an 80s F-series motor.
Ended up getting an EGR gasket for an 80s F-series motor.
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Ford Parts Specialist
Joined: Nov 2006
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From: Simi Valley, CA
First EGR valves on Ford vehicles: 1973.
The factory installed EGR/Carb spacer plates were aluminum. These aluminum spacer plates are notorious for getting clogged up with carbon, which can cause them to MELT internally.
The service part replacement (parts sold at Ford parts counters) plates were cast iron.
The factory installed EGR/Carb spacer plates were aluminum. These aluminum spacer plates are notorious for getting clogged up with carbon, which can cause them to MELT internally.
The service part replacement (parts sold at Ford parts counters) plates were cast iron.
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I had the plate off when I put the engine back together and I scraped out a good bit of carbon from it. Today I pulled the valve end off and it looked clear. I blew out the debris inside the valve end too. There really wasn't much inside. When I saw the cost for a new egr valve I just got the gasket instead.
Ford Parts Specialist
Joined: Nov 2006
Posts: 88,826
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From: Simi Valley, CA
I had the plate off when I put the engine back together and I scraped out a good bit of carbon from it. Today I pulled the valve end off and it looked clear. I blew out the debris inside the valve end too. There really wasn't much inside. When I saw the cost for a new egr valve I just got the gasket instead.
One gasket is used to mount the EGR valve to the plate. One THIN gasket is used between the spacer & manifold. One THICK gasket is used between the carb & spacer plate.
1973/79: The gaskets are not all the same for all models.
There are dozens of different carb/manifold & carb/spacer gaskets.
There are two different EGR valve to EGR/carb spacer plate mounting gaskets, because there are two different types of EGR valves.
Hotshot
Joined: Mar 2007
Posts: 10,101
Likes: 40
From: Pa
First EGR valves on Ford vehicles: 1973.
The factory installed EGR/Carb spacer plates were aluminum. These aluminum spacer plates are notorious for getting clogged up with carbon, which can cause them to MELT internally.
The service part replacement (parts sold at Ford parts counters) plates were cast iron.
The factory installed EGR/Carb spacer plates were aluminum. These aluminum spacer plates are notorious for getting clogged up with carbon, which can cause them to MELT internally.
The service part replacement (parts sold at Ford parts counters) plates were cast iron.
Yep, the one on my 302 is aluminum and it has some damage done by the exhaust heat pitting/melting the aluminum.(Completely clogged) I blasted it and it cleaned up real nice though. Its interesting that over the counter plates were cast iron.
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There were two gaskets that went between the valve and the plate. A metal gasket went between the two fabric gaskets. Do they still sell the thick gasket and thin gasket for 78' -79' EGR? I have my old thick gasket but its edges are opened up from years of hot and cold.
MSEE
Joined: Apr 2004
Posts: 10,386
Likes: 35
From: Austin, TX
There were two gaskets that went between the valve and the plate. A metal gasket went between the two fabric gaskets. Do they still sell the thick gasket and thin gasket for 78' -79' EGR? I have my old thick gasket but its edges are opened up from years of hot and cold.
Doesn't matter. It's an open/close switch. The two ports are connected above the temperature threshold, and isolated below the temperature threshold.
Ford Parts Specialist
Joined: Nov 2006
Posts: 88,826
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From: Simi Valley, CA
Originally Posted by NumberDummy
First year for EGR valves on Ford vehicles: 1973.
1977/79 F100/350 351M/400 // 1978/79 Bronco 351M/400 // 1977/78 LTD/Mercury Marquis 351M/400 // 1977/79 LTD II/Cougar/Ranchero/Thunderbird 351M/400
1977/79 Mark V 400 / 1979 Lincoln Town Car 400:
D7AZ9447B .. Gasket, Spacer to Intake Manifold (Motorcraft CG488) / Obsolete
E5HZ9C477A .. Gasket, Carburetor to Spacer (Motorcraft CG539A) / Available from Ford.
E5HZ9C477A replaced D7FZ9C477A.
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1973, barrel, carb, carburetor, cg539a, com, d7fz9c477a, difference, egr, ford, motorcraft, nonegr, ported, switch, systems, vacuum, valve
