First, how can I tell if I have a feedback carburetor currently on my truck? Being a 1985, I do know that it originally came with one, but it was replaced by my father about 12 years ago with a Motorcraft 2-barrel. There is a mysterious bundle of wires and plastic on both sides of the carburetor, but they don't lead to the carb or anything that I can see. Where these wires originally part of the EEC-IV and feedback carburetor?

Second, assuming that I do not have a feedback carburetor, would happens or what are the drawbacks to running a non-feedback carb with the stock TFI-IV ignition module (module located on the distributer)? Doesn't the TFI-IV ignition rely on computer signals from the carb?

My truck (302 2-barrel) starts right up and idles smooth, but is terrible on gas, and I am wondering if running a non-feedback carburetor with the TFI-IV ignition has anything to do with it.

 

My understanding is the truck will run fine but the vacuum advance won't change the timing so the engine won't reach it's full potential........so, it'll use a little more gas and won't be as "pepie" as it normally would be.

 

...the vacuum advance won't change the timing so the engine won't reach it's full potential." I don't quite understand. Can you explain this to me more? Does the TFI electronic distributer rely on a signal from the carburetor?

 

Not quite, it relies on everything working together to tell the computer how to control the ignition, the carberator etc..

With the non-feedback carb on the truck, the computer isn't getting any signals from the carb. Therfore the computer will place the emission and ignition system in "Limp Home" mode. Gas mileage and performance will suffer because of this.

The Computer will try and adjust the fuel mixture at the carb, but since it cant because of the non-feedback carb, it will adjust everything at a factory preset level so you can "Limp Home". Timing, emissions equipment, etc.. will be adjusted to a preset factory setting. Not where it needs to be adjusted at. If you get my meaning.


You have two options.

1: Replace the Carb with a feedback carb. Probably your easiest and simplest bet to get the truck fixed right away. But then you will have to go through the computer and TFI-IV system and check for and replace faulty parts. May get costly $$$, but not neccessarily. Just depends on how many faulty parts you come across.

2: Replace your ignition and distributor system with a Duraspark II. Not the easiest thing to do, because there is rewiring and things that could get complicated. This way you could get rid of all your smog devices, computer etc..., (If legal in your county or state) so that could be a plus in favor if doing it. Would be cheaper to do $$$, but more labor intensive, and complicated of a swap. You wouldn't get the truck back right away either, cause of all the changes that would have to be made etc... Can take anywhere from a day to a week on average to do a swap like this, depending on skill level.


It all depends on your automotive skills, or what you are wanting or think you yourself can handle. Then choose the option you are most comfortable with.

The truck will never run, or perform right or get good gas milage with it the way it is now though.

Hope this helps,

 

81-F-150-Explorer, I think I understand it now. I would like to have my '85 Ford run efficiently and reach its potential. My truck already has the smog equipment stripped off by the previous owner (and dual exhaust with no cats) and I don't know what else is missing or non-functional. Right now, though, my gas mileage is terrible, the timing always seems off, and my truck lacks any power. I was thinking of replacing the 2-barrel for a Holley 4bbl carburetor, so I might just go with option #2 in your post. What all is involved with this swap? Are there any articles or write-ups that could tell me exactly what year(s) Duraspark II ignition would be campatible with my 1985 F-150 302? LMC Truck lists several Duraspark models for different years. Should I stay with Ford ignition/distributer or go aftermarket? Thanks!

 

The ECC is setup for the disposition of the truck at hand.

Rear axle transmission,etc

You would need to eliminate it entirely from the engine operation side of things and revamp those things.

One thing:
Since the computer also controls the electric fuel pumps that system would require a different actuating system as in oil pressure switch, plus, "I think" you would need to regulate the fuel pump pressure down to 7-9 psi to accomodate the new carb.

I'm sure others have more in-depth info than I do

 

Ok Option Two would definatley be the cheaper way to go for you.

If you go to the 302 Forum, there will be some very nice people there that can help you with that swap, that understand it better than I do.

If the truck had a carb to begin with, I would assume it has a mechanical fuel pump on the engine somewhere. Double check that with the 302 forum though. There was a lot of changing going on during the middle 80's with Ford at that time. I only kept up with the 300-I6s etc...

I would find a Duraspark II system that is "blue" tab. From around circa 1979. You would need the distributor, the complete wiring, and the module. And some rubber vacuum hose to hook up the mechanical vacuum advance.

As I said, the 302 forum will be your best bet for more info.

Hope this helps get you started.

 

Good info guys. The BLUE TAB Duraspark are on 86 F250s. They were the most popular used.

 

Okay...the BLUE TAB Duraspark. Can you be more specific? I am sure that if I went to NAPA or Advance Auto they are not going to know what I mean if I just tell them BLUE TAB Duraspark. Where can I get one, and how exactly do I describe what I need? Any specific year, or model number? Where would I find the wiring harness, and what years? Thanks!

 

I would ask for a Duraspark II, Blue tab, module, and distributor with, single port vacuum advance for a 1979 302-V8. You may also need the coil as well.

The wiring....


I do believe there is a wiring kit for the 302-v8 somewhere out there for this conversion that the mustang buffs use. I do remember reading about that somewhere. That's all I know about that however. The 302 forum would be of more help here.

Alternatively you can scavenge the junk yards for the Duraspark II wiring harness. A good junk yard will be able to give you a cross reference sheet on which models are compatible etc.

hope this helps...

 

By blue tab,

He means the Blue epoxy under the unit that secure the wires to the module.

They are normally called: Blue Grommets.


The Carburetor

Wasn't that feedback carb a TBI carb ?

 

What about the Pertronix Billet Plug-and-Play distributers? (Summit Part #PNX-D130711) Would this work as good as the Duraspark? Can I use the TFI coil with this, or would I have to use their Flame Thrower ignition coil?

 

personaly i like the msd ignition set up. i just bought an installed, there billet aluminum vacuum advance distributor, msd 6 ignition box, blaster coil and there msd super conductoer wires, easy to hook up and works great.

 

Hi,

Review our line of D.U.I. and Duraspark distributors before you make a decsion at:
http://www.performancedistributors.com/forddui.htm

 

FTE sponsor:

In regards, to the distributors you mention .

there seems to be an application problem here.
ie:
#32820 Ford 351C-400M-429-460 $369.00

The application should be
351C/351M/400/429/460

You may want to get the web site person to change the mention of 400M to just 400.

There is No M after 400.
The M comes after 351 and in 351M