emissions equip question
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emissions equip question
The previous owner of my truck really tore apart the emissions equipment. What's my best course to ensure I'm not having performance issues. It is an 81 f100 with the 300 i6 and c6 trans and if it matters its duraspark 2 the egr valve is still present at the egr plate though disconnected and that inch or so diameter steel pipe below has be cut and bent back on itself I assume to try and seal it and the truck has many plugged vacuum ports it runs and idles kinda weakly. And has a very intermittent misfire. I don't see pretty much any other emissions equipment. There are quite a few other possible contributing factors to my issues but for know I wanted to see if there are any recommended solutions to finishing removing the emissions equip to eliminate it as a possible cause.
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From: Virginia
Study the diagrams and function of the late 60's early 70's versions of your engine. Make yours more like those. The only thing you need to watch out for;
Pinging. If the engine tends to rattle when you step on the gas, you will need to do some tuning or hook the egr back up. Some engines tend to do it, some don't. Just try it and see what happens.
I would hook the original aircleaner and all it's vacuum lines back up and install the heat hose from the exhaust manifold to the aircleaner snorkel.
Go over all the vacuum plugs in the system. I have seen these plugs you buy in the store crack and leak. They are not made of very good quality rubber.
Pinging. If the engine tends to rattle when you step on the gas, you will need to do some tuning or hook the egr back up. Some engines tend to do it, some don't. Just try it and see what happens.
I would hook the original aircleaner and all it's vacuum lines back up and install the heat hose from the exhaust manifold to the aircleaner snorkel.
Go over all the vacuum plugs in the system. I have seen these plugs you buy in the store crack and leak. They are not made of very good quality rubber.
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Thanks for the help I replaced all vacuum lines and caps and I will study those diagrams once I find them I searched the forums and read up on vacuum tuning and tuned my carb and timing via vacuum and am running 20 vacuum and it doesn't seem to ping. My main worry is the inch diameter pipe my phone auto corrected but what I meant was they have already cut the pipe and bent it up on itself and I was wondering if there is anything I should do to keep that from being a performance issue.
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From: Virginia
As long as the engine is not pinging, don't worry about the egr. You might want to take the egr off and check the gasket, and possibly make a new gasket to block it off solid. The egr can leak and create a vacuum leak. In your case, it probably will not be a problem unless there is still a little crack in the folded pipe that can suck vacuum if the egr was leaking.
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From: Northeast, OK
Your MPG may be very poor without either the EGR or re jetting. The exhaust gas from the EGR leans the air/fuel mix so the carb is jetted to account for that. But when you remove the EGR that leaves the air/fuel mix quite rich.
So, if MPG is important to you I would recommend one of two approaches. The least expensive would be to find out what jetting Ford used in that carb before EGR, and one way would be to ask the people in the 60's forum - probably the same ones that you ask for the vacuum diagrams. The other approach is to buy a rebuilt carb for an engine from the pre-EGR era. One of our guys, 1986F150six, has done just that and is getting 18 - 22 MPG, although he drives very gently and has a tranny with OD.
So, if MPG is important to you I would recommend one of two approaches. The least expensive would be to find out what jetting Ford used in that carb before EGR, and one way would be to ask the people in the 60's forum - probably the same ones that you ask for the vacuum diagrams. The other approach is to buy a rebuilt carb for an engine from the pre-EGR era. One of our guys, 1986F150six, has done just that and is getting 18 - 22 MPG, although he drives very gently and has a tranny with OD.
Lead Driver
Joined: Jul 2009
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From: Sheffield, AL
The carburetor, which Gary alluded to, is a Carter YF 4901 S, which came from a 1970 F350 with 300 engine.
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FTE Legend
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From: Northeast, OK
As an example of what can be significant differences in carbs, Bruno borrowed an Eddy 1405 that made his Bronco run quite well. So we thought we would jet his 1406 to match since Edelbrock says it is jetted leaner to increase MPG. However, we discovered that isn't possible as there are significant differences in things like primary and secondary boosters, and those parts are not available to purchase.
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From: Virginia
Your MPG may be very poor without either the EGR or re jetting. The exhaust gas from the EGR leans the air/fuel mix so the carb is jetted to account for that. But when you remove the EGR that leaves the air/fuel mix quite rich.
So, if MPG is important to you I would recommend one of two approaches. The least expensive would be to find out what jetting Ford used in that carb before EGR, and one way would be to ask the people in the 60's forum - probably the same ones that you ask for the vacuum diagrams. The other approach is to buy a rebuilt carb for an engine from the pre-EGR era. One of our guys, 1986F150six, has done just that and is getting 18 - 22 MPG, although he drives very gently and has a tranny with OD.
So, if MPG is important to you I would recommend one of two approaches. The least expensive would be to find out what jetting Ford used in that carb before EGR, and one way would be to ask the people in the 60's forum - probably the same ones that you ask for the vacuum diagrams. The other approach is to buy a rebuilt carb for an engine from the pre-EGR era. One of our guys, 1986F150six, has done just that and is getting 18 - 22 MPG, although he drives very gently and has a tranny with OD.
In my real world experience, the engine seems to run a little bit leaner, but I am not positive about that because I have read the EGR slows the combustion process, and somehow makes the combustion process cooler. This keeps the emissions down(is it NOx?) and keeps it from pinging. I am not sure if this is "leaner" or something else going on.
It makes sense in a way though, if you have a certain size chamber in the head, and part of it is inert exhaust gas, and the air and the fuel have to fill up what is left, you can assume if the exhaust gas is taken away, then all that will become air. I know that is not totally true though, since I have noticed without the EGR, you can lift your foot off the gas pedal a little bit and still be going the same speed as with the EGR.
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From: Northeast, OK
I am not too positive how the EGR system works out in the end. The exhaust gas is inert, it doesn't lean or richen the mixture, it just takes up space in the combustion chamber.
In my real world experience, the engine seems to run a little bit leaner, but I am not positive about that because I have read the EGR slows the combustion process, and somehow makes the combustion process cooler. This keeps the emissions down(is it NOx?) and keeps it from pinging. I am not sure if this is "leaner" or something else going on.
It makes sense in a way though, if you have a certain size chamber in the head, and part of it is inert exhaust gas, and the air and the fuel have to fill up what is left, you can assume if the exhaust gas is taken away, then all that will become air. I know that is not totally true though, since I have noticed without the EGR, you can lift your foot off the gas pedal a little bit and still be going the same speed as with the EGR.
In my real world experience, the engine seems to run a little bit leaner, but I am not positive about that because I have read the EGR slows the combustion process, and somehow makes the combustion process cooler. This keeps the emissions down(is it NOx?) and keeps it from pinging. I am not sure if this is "leaner" or something else going on.
It makes sense in a way though, if you have a certain size chamber in the head, and part of it is inert exhaust gas, and the air and the fuel have to fill up what is left, you can assume if the exhaust gas is taken away, then all that will become air. I know that is not totally true though, since I have noticed without the EGR, you can lift your foot off the gas pedal a little bit and still be going the same speed as with the EGR.
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Thanks for the carb recommendations I'll have to check into that and making an egr block ooff and plugging the hole for the pipe. Though I think it would be kinda cool to get that offenhauser intake and 4 barrel if the motor stays running good for a while because as of right now after a good tune up and vacuum tuning and all new vacuum lines she is idling really smooth and running great minus my insane amount of oil blowing out of the breather. And mpgs are not currently a concern because I can't even track them reliably until I buy a gas tank that doesn't leak.
Lead Driver
Joined: Jul 2009
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From: Sheffield, AL
The one I have is listed as C6002. It has the hot air choke, but I converted to a manual choke.
The C666 is manual choke from the beginning.
Be advised, that the mounting stud measurement changed at some later date and the two holes on either of the above two carburetors will need to be elongated just a little. This is not hard and took me about 15 minutes with a round file. I used the new carburetor base gasket [for your 1981 engine] as a template.
By the way, I was very impressed with the quality of the Autoline remanufacturing process. The throttle shaft had been rebushed and the carburetor required only a very slight idle air/fuel adjustment "right out of the box". The carburetor is now 4-5 years old and still performs admirably. Ask Gary about his observations regarding the AFR of this set-up.
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From: Northeast, OK
David is right - the AFR is apparently just right. I put my wideband AFR meter on and expected to find a rich condition which would require leaning the carb out. But, the readings we got were every bit as lean as I would have wanted. And yet the engine runs quite well and exhibits no symptoms of being too lean. So we called it good and finished that part of the process.