Emissions Control Restrictions?
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5th Wheeling
Joined: May 2020
Posts: 37
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From: Massachusetts
Emissions Control Restrictions?
Hi guys, Im 16 and I have a 1979 F150 Supercab 4x4 with a 400ci engine and 4-speed Manual. I know there's a lot of emissions control devices on the engine, and I'm wondering if there's any way I can remove these. I believe its mostly hoses to reuse exhaust fumes and a vacuum regulated distributor. Can I simply remove all the hoses and plug the gaps, or is it a more technical thing the replace? Anything you know would be much help, as I know very little about stuff like this, still learning. Thank you in advance.
Lead Driver
Joined: Nov 2006
Posts: 5,217
Likes: 506
From: Pa.
Have a look over here. People disconnect the emissions more specifically the EGR because they don't understand how it works or they don't know how to reconnect it because the previous owner left it in a state of chaos. First on the drivers side valve cover if a V-* motor there should be a label. If it is still there take a picture and post it. It will tell us the calibration code for the motor and tell us what emissions diagram is relevant to your specific truck and what emissions equipment it came with from there we can reconnect things in there proper place and put back any missing bits.
That all being said the 400M never existed in a moment in time like say the Ford FE motors did where it had no emissions so taking away the emissions isn't something that should be randomly done without understanding what the consequences are and what needs to be done to correct any adverse effects that are a result of taking the emissions away. A recurving of the distributor is one of a few things that should be done if you remove the original emissions on a 351/400 M motor. You decide and we will advise you what you do next.
The EGR is only supposed to work when 2 conditions are met.
The first is that it's getting vacuum. Manifold vacuum specifically. Manifold vacuum is at it's highest when you're idling or maintaining speed. When you punch the throttle, the throttle-valve in the base plate opens and the vacuum inside the motor is offset by the atmospheric pressure. That is, manifold vacuum (below the TV) drops and ported vacuum (above the TV) starts to come in.
The second condition (on other motors, your diagram looks like it shows different) is when the ported vacuum switch that sits on top of the heater hose fitting opens up. The way this works, as the motor heats up, the coolant heats too. And, as the coolant heats, there's a bi-metallic spring inside of the PVS that acts just like the spring on an electric choke. As it warms up, it opens. This allows vacuum to flow through the PVS.
So, the EGR only works when you've got high manifold vacuum (cruising, idle) and when the motor is warmed up (coolant), and it shuts off when your step on the loud pedal to go fast (lack of manifold vacuum to hold the diaphragm open).
So you can see why the stories that people tell you about disconnecting the EGR on a stock engine are BS. An EGR doesn't take anything away from power, and only increases the MPG's of the motor by using exhaust gases to take up space in the cylinder (gas and fresh air can't flow in when the space is already taken
). Disconnecting the EGR on a stock motor can also result in pinging or ignition knocking as the distributors are specifically curved to run with an EGR, as the EGR lowers combustion chamber temperatures.
The first is that it's getting vacuum. Manifold vacuum specifically. Manifold vacuum is at it's highest when you're idling or maintaining speed. When you punch the throttle, the throttle-valve in the base plate opens and the vacuum inside the motor is offset by the atmospheric pressure. That is, manifold vacuum (below the TV) drops and ported vacuum (above the TV) starts to come in.
The second condition (on other motors, your diagram looks like it shows different) is when the ported vacuum switch that sits on top of the heater hose fitting opens up. The way this works, as the motor heats up, the coolant heats too. And, as the coolant heats, there's a bi-metallic spring inside of the PVS that acts just like the spring on an electric choke. As it warms up, it opens. This allows vacuum to flow through the PVS.
So, the EGR only works when you've got high manifold vacuum (cruising, idle) and when the motor is warmed up (coolant), and it shuts off when your step on the loud pedal to go fast (lack of manifold vacuum to hold the diaphragm open).
So you can see why the stories that people tell you about disconnecting the EGR on a stock engine are BS. An EGR doesn't take anything away from power, and only increases the MPG's of the motor by using exhaust gases to take up space in the cylinder (gas and fresh air can't flow in when the space is already taken
). Disconnecting the EGR on a stock motor can also result in pinging or ignition knocking as the distributors are specifically curved to run with an EGR, as the EGR lowers combustion chamber temperatures.
Post Fiend
Joined: Feb 2008
Posts: 5,831
Likes: 121
From: St Albert, Alberta
Have a look over here. People disconnect the emissions more specifically the EGR because they don't understand how it works or they don't know how to reconnect it because the previous owner left it in a state of chaos. First on the drivers side valve cover if a V-* motor there should be a label. If it is still there take a picture and post it. It will tell us the calibration code for the motor and tell us what emissions diagram is relevant to your specific truck and what emissions equipment it came with from there we can reconnect things in there proper place and put back any missing bits.
Quote:
The EGR is only supposed to work when 2 conditions are met.
The first is that it's getting vacuum. Manifold vacuum specifically. Manifold vacuum is at it's highest when you're idling or maintaining speed. When you punch the throttle, the throttle-valve in the base plate opens and the vacuum inside the motor is offset by the atmospheric pressure. That is, manifold vacuum (below the TV) drops and ported vacuum (above the TV) starts to come in.
The second condition (on other motors, your diagram looks like it shows different) is when the ported vacuum switch that sits on top of the heater hose fitting opens up. The way this works, as the motor heats up, the coolant heats too. And, as the coolant heats, there's a bi-metallic spring inside of the PVS that acts just like the spring on an electric choke. As it warms up, it opens. This allows vacuum to flow through the PVS.
So, the EGR only works when you've got high manifold vacuum (cruising, idle) and when the motor is warmed up (coolant), and it shuts off when your step on the loud pedal to go fast (lack of manifold vacuum to hold the diaphragm open).
So you can see why the stories that people tell you about disconnecting the EGR on a stock engine are BS. An EGR doesn't take anything away from power, and only increases the MPG's of the motor by using exhaust gases to take up space in the cylinder (gas and fresh air can't flow in when the space is already taken ). Disconnecting the EGR on a stock motor can also result in pinging or ignition knocking as the distributors are specifically curved to run with an EGR, as the EGR lowers combustion chamber temperatures.
That all being said the 400M never existed in a moment in time like say the Ford FE motors did where it had no emissions so taking away the emissions isn't something that should be randomly done without understanding what the consequences are and what needs to be done to correct any adverse effects that are a result of taking the emissions away. A recurving of the distributor is one of a few things that should be done if you remove the original emissions on a 351/400 M motor. You decide and we will advise you what you do next.
Quote:
The EGR is only supposed to work when 2 conditions are met.
The first is that it's getting vacuum. Manifold vacuum specifically. Manifold vacuum is at it's highest when you're idling or maintaining speed. When you punch the throttle, the throttle-valve in the base plate opens and the vacuum inside the motor is offset by the atmospheric pressure. That is, manifold vacuum (below the TV) drops and ported vacuum (above the TV) starts to come in.
The second condition (on other motors, your diagram looks like it shows different) is when the ported vacuum switch that sits on top of the heater hose fitting opens up. The way this works, as the motor heats up, the coolant heats too. And, as the coolant heats, there's a bi-metallic spring inside of the PVS that acts just like the spring on an electric choke. As it warms up, it opens. This allows vacuum to flow through the PVS.
So, the EGR only works when you've got high manifold vacuum (cruising, idle) and when the motor is warmed up (coolant), and it shuts off when your step on the loud pedal to go fast (lack of manifold vacuum to hold the diaphragm open).
So you can see why the stories that people tell you about disconnecting the EGR on a stock engine are BS. An EGR doesn't take anything away from power, and only increases the MPG's of the motor by using exhaust gases to take up space in the cylinder (gas and fresh air can't flow in when the space is already taken
). Disconnecting the EGR on a stock motor can also result in pinging or ignition knocking as the distributors are specifically curved to run with an EGR, as the EGR lowers combustion chamber temperatures.That all being said the 400M never existed in a moment in time like say the Ford FE motors did where it had no emissions so taking away the emissions isn't something that should be randomly done without understanding what the consequences are and what needs to be done to correct any adverse effects that are a result of taking the emissions away. A recurving of the distributor is one of a few things that should be done if you remove the original emissions on a 351/400 M motor. You decide and we will advise you what you do next.
Hate to say it but whoever said that about the EGR does not have a full understanding of the EGR. Not by a long shot.
For the op check your local requirements first before you pull anything off as you may need it to be in place. And not all the stuff needs to go depending on where you are some should stay.
If you post a pic of the emissions sticker the system can be modified and rerouted to suit whatever needs you have. Being a former Ford engineer that did primarily emissions systems in the era when this stuff was being used I'm quite familiar with it and modding it.
Super Moderator
Joined: Apr 2004
Posts: 34,526
Likes: 2,830
First off does it run ok now? Does it start easily?
The things that are "wrong" with a 400 performance wise can't be fixed by taking the external emissions stuff off. You can make it run worse of course, but for meaningful performance improvement, it needs pistons that give it higher compression and a cam that opens the valves differently. And that's just the start.
So if it runs good, drive it. If it's off a bit, check the usual suspects like carb adjustment and spark plugs.
Some of that stuff, when working properly, actually "helps". PCV system keeps the mung from building up inside the engine. EVAP system keeps your gas from evaporating as fast, and keeps the fumes away. Unless you like gas fumes....
The things that are "wrong" with a 400 performance wise can't be fixed by taking the external emissions stuff off. You can make it run worse of course, but for meaningful performance improvement, it needs pistons that give it higher compression and a cam that opens the valves differently. And that's just the start.
So if it runs good, drive it. If it's off a bit, check the usual suspects like carb adjustment and spark plugs.
Some of that stuff, when working properly, actually "helps". PCV system keeps the mung from building up inside the engine. EVAP system keeps your gas from evaporating as fast, and keeps the fumes away. Unless you like gas fumes....
Post Fiend
Joined: Feb 2008
Posts: 5,831
Likes: 121
From: St Albert, Alberta
This has been written up multiple times already on this board the information is there and available. Here is one to get you started https://www.ford-trucks.com/forums/1...issions-5.html
And just an FYI the timing curve has NOTHING to do with why an engine may ping after the EGR is removed.
And just an FYI the timing curve has NOTHING to do with why an engine may ping after the EGR is removed.
Last edited by 85e150; Apr 5, 2021 at 02:39 PM. Reason: OT comments removed
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