Carb conversion to Non feedback
 

Hello all. I have a 1984 F150, 4x4, 351W, C6, 3.55LSD with electronic feedback carb (EFC). I want to backdate it to get rid of the EFC and computer. I think i have the Duraspark conversion mapped out but was curious if it is feasible to convert the EFC to non EFC or am I better off just picking up a used carb and rebuilding. If converting is feasible that might save some money as I am retired. Anyone ever tried to convert a carb from feedback to Non feedback. Thanks!

I have never done it, but I would imagine you would need another carb for parts to convert it, so you might as well rebuild the parts carb and use it. The electronic carb is most likely jetted differently, with a different calibration to work with the fuel supplied by the electronic part of the carb.

I haven't converted a carb, but have converted the engine by bolting on a non-feedback carb and eliminating the computer and associated wiring/sensors. The 2bbl Autolite 2150 carbs are pretty inexpensive so I'd get one and rebuild it.

Thanks guys. Looks like it is time to hit the junkyard and find a 2150 and the parts for the Duraspark conversion.

At least in '82 the sensors and associated wiring was completely standalone, so taking it out was easy and clean.

To swap out the feedback system to Duraspark you'll need the harness from the round-ish plugs on the inner fender to the dizzy/coil/oil and water tem senders, the coil, the module, and the dizzy.
Your present carb will work, but will run rich, so getting a used carb and rebuilding it is a good move.
The ignition system is plug and play; you'll unplug the TFI system and the DSII system will plug into the same connectors. Before you start, make sure you can adjust the dizzy for timing; some of the newer feedback systems had a "notched" distributer that couldn't be adjusted; I'm unsure how to advise you in dealing with that.
Have fun.

Lots of stuff in the sticky about DSII swaps....

If you want to save money just run your current feedback Carb. I got 17 MPG on my last 200 mile road trip with a feedback carb. I dont believe it is cost effective to spend money on another carb as the pay off would take to long.

Do you have to do emission testing in your state?
Here is a good read.
https://www.ford-trucks.com/forums/9...gnition-3.html.

I dont believe you can convert a carb.
Jim

Jim - Is your carb running in feedback mode? IOW, is your computer running it?

No... I removed the computer.
The info is in the bottom of my post, in the signature line.

I did about 3 months of testing with a push button connected to the feedback solenoid, driving it full lean when ever possible. I had a DVM connected to the O2 sensor to monitor it.
After 3 months of manual operation I didnt have ANY change in my gas MPG.
And thus I will keep running the current feedback carb until it wears out.
Jim

I'd do the same if I got the same results. Good test and good to know.

How so did you run the feed back manuelly i am interested being a truck i just bought has the return fuel line cut and plugged trying to better understand the system better to get things running right it runs way rich right now

hello I was wondering if you would Know the answer to a question? Cand i use the computer ran dizzy with a standard none feed back carb? And second question is more of how did you get you feedback carb to run without the computer? do you have to convert to a duraspark two do that. interested in making that conversion. I have a 84 f150 4.9L auto trying to figure out what is my options are to getting it running solid and not smelling gas all the time?

I know you aren't asking the question of me, but I will answer nonetheless. You can run the "computer dizzy" with a standard non-feedback carb but you will not like the result. By saying "computer dizzy" I'm assuming you mean that you would also continue to run the computer, as that would be required to fire the distributor. However, that computer would not be happy because it would realize via the O2 sensor via which it monitors the air/fuel ratio that it is not able to change that ratio since it doesn't have control of the carb. At that point it will go into "limp home" mode and lock the ignition timing at something like 10 degrees. Your engine will run, but poorly.

As for how Jim ran that carb, he explained - he installed a push button that turn on the solenoid that the computer used to adjust the air/fuel ratio and monitored the result via the O2 sensor. Since he didn't see any benefit he took the computer out. But, when you remove a computer on these systems you must convert the ignition to DS-II. Or else you will effectively be in limp-home mode since the computer is what gives that ignition its advance. IOW, w/o the computer you have no advance.

If your current feedback carb is not working correctly, “smelling gas all the time”, I would just replace it with a older style carb and doing a DS2 conversion. I do not recommend putting any money into repairing a feedback carb unless you live in California and/or have to due to local emission requirements.

The feedback carb I am currently running is a replacement feedback carb I bought on ebay for $50. It was a fresh overhaul, but after I got ready to install it I realized it did not have a TPS on the front of the throttle shaft and thus was not compatible with an 1986 computer system. At this point I just got rid of the computer. I decided to keep on using the ebay feedback carb as it did not have any negative effect on my MPG.

At speed above 55-60 mph the O2 sensor indicated the mixture was lean anyway and I get 17 mpg on a road trip with speeds about 60-65 mph.

All this really just means I am to cheap to buy the correct carb. :o

Jim