I just bought a truck that some one pulled the EGR off and it spark knocks really bad, and blows lots of black smoke at idle. I found tons of vacume leaks and lots of other stuff that is amiss, but the EGR is blocked off with a couple of layers of corrigated tin roofing that has been hammered flat. Back to the original subject, does any one have a vacume diagram and do I need to hook all the temp switches back up (like the one in the thermostat housing)? Also the steel line that comes out he bottom is still there but there is another large port right under the carb that is plugged and I think it is where the exhaust reentred the intake. Where can I find this line other than a junk yard, none of them around here have any Fords of this era. Oh it is a 79 F150 2wd with a 300 six and a 4spd.
-Johnboy

 

I'm guessing that the front of your engine bay doesn't have a vacuum diagram sticker on it. They generally do, and the 300 is simple enough that it's an easy diagram to follow. If not, I'll try to get you a picture of mine. It's an '81 and I'm sure they're rather similar.

If you simply want to get the EGR working, all you need to do is find a vacuum source that is 0 at idle, and pulls vacuum under acceleration. Get an EGR gasket from the parts store (like $5), and an EGR valve if you don't have one. I wasn't sure by your description if the valve was still there (just blocked off).

Then, there is a pipe that comes out from the exhaust manifold and back up underneath the EGR spacer. This is pretty much all you need to get your EGR working. When the engine is under a load, the vacuum pulls the valve open, and allows exhaust to come from the exhaust manifold back into the combustion chamber. I don't believe anyone makes this line, so it's either a junk yard part, or custom. If you're good at bending pipe, you can make one pretty easily. Or, make one out of plumbing parts so you can use elbows and stuff like that. Just be sure they can take the temps.


As for the rest of the vacuum lines, they were there for a reason, but if your engine is running well, and you have an acceleration-only vacuum on the EGR valve, they weren't necessary.

 

I figured I would just use the vacuum source that says EGR on the carb that didn't have a hose on it, I just need to find that steel line.
-Johnboy

 

The line from the exhaust to the EGR can be custom fabricated...fittings and adapters and a household appliance gas line of the appropriate length and you are good to go. Ace Hardware is a good place for the parts.

 

Don't run the EGR valve directly from ported vacuum; there needs to be a ported vacuum switch in between. These thread into a water jacket; on the 300 it's usually part of the thermostat housing. This prevents the EGR valve from opening before the engine reaches operating temperature.

That plugged fitting you're talking about sounds like the check valve for the smog pump, but I can't tell from your description. On a '79 there would have been a spacer plate with two openings. One faces downward and runs to a large pipe on the exhaust manifold; this is for EGR. One faces toward the front of the truck and is for the smog pump check valve.

 

I was talking about the one on the front, it is plugged. Did they plug them from the factory? So for the vacuum line I should run it from the port on the carb marked EGR to the top or bottom? of temp switch in the thermostat housing then to the EGR valve.
-Johnboy

 

Not sure about the plug. I think you either had both the smog pump and EGR, or neither - in which case there wasn't this spacer plate. Again, I'm not sure.

For the vacuum line, it doesn't matter which goes where on the ported vacuum switch. The switch is either open or closed.