On my 85 f-150 5.8L HO 4v I just took off all my smog system stuff, since most of it was not working and leaking anyways. I was wondering if the timing needs to be changed now or if any settings need to be changed on anything. The truck doesn't seem to run the same with it off, as far as acceleration goes, but that may just be paranoia on my part. It also sounds throatier for some reason, but that could just be my mufflers continueing to rot off.

Thanks

 

I have an '85, but with the 300-six. Without signals from certain sensors, the computer may not be able to set timing. It can substitute a default value for some things that are missing, but others put the computer into "limp home" mode and there is no spark advance. Might depend on which distributor and ignition system you have.

The Haynes manual describes these systems well enough to get the basics and talks about this.

-Ed

 

I don't have any computers though that I know of. Are there computers in the carburate 351? I know there were some crazy looking things on the drivers side fender that had vacuum lines going to them. I'll go check those little guys out i guess, and see if i can come up with anything. mabey i should search for the part numbers to see what they are called..

 

i took a picture of the two things that had electrical stuff on them, can anybody tell me what they are? they are in my gallery.

 

Mine was halfway stripped down, nothing like that on mine, but it's a 300-6.

-Ed

 

Ok, those are vaccume solonoids and switches...

The one on the left switches vaccume on or off depending on when the solonoid is energized or not. Usually hooked up to a EGR valve, or Thermactor valves, for controlled switching on or off by a computer through vaccume.

The one on the right switches on an electrical current through a wire when vaccume is present. Usually hooked to a ported vaccume switch. When vaccume is present at the switch the switch closes and alows current to go through the wires to tell the computer that the engine is hot, or that you are at full throttle, or closed throttle, or numerous different functions depending on year and engine. The switch is normally color coded and different colored switches react to different vaccume "pressures" and closes with little vaccume, or needs quite a bit to close. etc...

Hope this helps.

 

I timed and set my rig mostly by ear, since I don't own a light, tach or vacuum gauge. It always had a miss till I put in a carb kit, after that I could get most settings closer to normal and the engine ran a lot smoother afterwards. I have no idea what smog stuff that's left might be contributing or not at this point but it sure runs good, better than it ever has in the year that I've owned it.

-Ed

 

so do i need the electrical switch one? Is it part of the emissions stuff, or does it actually affect the way the truck runs?

 

Jpjahn; If you have a TFI distributor, you have a computer that adjusts the timing. The computer is usually mounted inside the cab up under the dash. A DuraSpark distributor has a vacuum advance and does not rely on a computer to adjust the timing. The TFI distributor does not have a vacuum advance and relies on a computer to set the timing.

I would recommend that the first thing you should do is to check your local emissions laws. If your state inspection includes a visual under-the-hood check, you might want to consider putting all that emissions stuff back on. If you are lucky enough to live where there are no inspections, at least get a timing light and check your base timing and timing advance.

SmokyOlFord’s advice is right on. If you have a TFI system, the computer takes inputs from various sensors on the emissions components. Based on those inputs, the computer adjusts the timing. Without those inputs, the computer just shuts down and reverts to what Ford calls a “limp-home” mode. The limp home mode defaults the timing to some preset value that is just good enough to get you home. Power, drivability, and gas mileage really suffer in the limp home mode. Considering the price of gas, if you have a TFI system that is in the limp home mode, it may be a good idea to retrofit to a Duraspark system.

If you now have a DuraSpark system, none of the above applies to you. If you do have a TFI system, the good news is that it is easy to replace the TFI system with a DuraSpark system.

 

I do live in an area where there are no emmissions laws so i'm good there.

I also just looked under the hood to check out the little ignition box on the drivers side fender, and it says Duraspark ignition. So i'm good to go there as well..

 

He's got plain ol' Duraspark. No computer. You are lucky for no emission laws, because this motor won't pass with them(laws). Mine barely passes with everything working. From your picture One item to the left looks to be TAD/TAB. EGR controls, and the other one I can't place yet. Just make sure you have no vacuum leaks. This thing has vacuum everywhere.

 

As for the crazy looking things on driver side w/ wires and vacuum near the fender. Did it come with cruise control? Thats whats over there.

Also what did you do, about the pipe that runs from head to head across the back of the motor? If you just took the hose off, you'll get that sound.

 

Taking all the things off was originally because of all the vacuum leaks that i had already, plus you could hardly see the engine because of all the hoses that went all over.
No i dont have cruise control, I wish i did.
I left the hoses, along with the little spout thing, and put huge bolts in it with the original clamp, to hold it tight

 

If you have a duraspark ignition that is good. Nothing that you have removed should effect timing, except for perhaps a spark retard solonoid to control pinging.

Do you have a feedback carb though? If so the vaccume switch on the right could control Wide open or closed throttle inputs to the computer, to control fuel mixture settings, or it is telling the computer when the engine is hot etc.... Sort of a pre-throttle position sensor or temerature switch of sorts, but instead of being controlled by wires directly it uses vaccume instead. Could make your truck run poorly if not working proper cause of the fuel mixture adjustments.

The one on the left shouldn't effect driveability at all, and is just an emissions component only. Probably Tab or Tad or EGR.

If you do have a feedback carb, I'd suggest if you don't have emmisions controls in your state, that you convert it to a regular carb and cut out the computer all together. It would run a lot better especially with components missing in the system.


Hope this helps