Hey yall i just got an 84 f150 4.9l 4 speed 2wd. i traded an 89 camaro for it. this is my first gas truck have had a few and still have an old 6.9l Any way i have always been told good things about the 4.9l so i figure it will be the next best thing to getting yet another 6.9l diesel. Slow, torquey and live forever just how i like them. Any way my concern is that the carb on it is from a 78 so its a non feed back right? Try and cope here im more of a diesel guy. How ever it still has the stock 84 ignition set up with the control module on the dizzy. No vac lines on the carb are connected. however the truck runs good a little rich and rough here and there. but seams strong. my concern is that it has no way to tell the dizzy to advance. Is this bad could it cause damage in the long run or just hurt fuel millage. Or are you going to tell me you have no clue how it is even running never mind well. like i said im kinda new to this. but am very mechanically inclined. i was going to start trying to figure out how to lean the carb up a bit but i figured maybe i should put the right ignition set up on it first. Also i have no clue how long it has been like this. Should i put an ignition system from a 78 so it maches the carb i really dont want any of the emision stuff on the truck. I want it easy and old school. Any info would be helpful. much obliged.

 

I have an '84 too, 4 speed, 4x4. Currently, I'm running the same kind of set up. I swapped out the feedback carb for a non-feedback carb off of an earlier model, and as of yet I haven't switched over the ignition system to match it. The only problem that I've had with running the newer ignition with the older carb is decreased gas mileage and power.
HOWEVER.
I just went to the junk yard today and picked up all the parts that I need to convert my ignition over to the Duraspark II system from the earlier years. All that you would need to do this, is a Duraspark II ignition module, the Duraspark II distributor which has a single vacuum advance on it, the distributor cap to match the dizzy, the wiring harness from an '80-'83, and a Duraspark compatible ignition coil. All of these parts can be found on an F-Series from the late '70s models, all the way up to '83.
From my understanding, it's pretty simple, really. Once you have all your parts, you swap in the new distributor and coil, install the ignition module, plug in the wiring harness to its respective plugs, do the timing on the truck, run a vacuum line from the dizzy to the carb and you're done. And then, if you want, you can remove all the excess vacuum lines and wires.
I haven't started on this conversion yet, but I plan to do it, if not this week, then this weekend. Let me know if you have any questions, I'll try to answer them as best as i can.

EDIT: Forgot to mention, it was $78.16 at the junk yard for all the parts that I needed. Pretty good, considering a brand new distributor was like seventy bucks.

 

Wow, advice from a new member that is every bit as clear and consise as what would come from a long-timer. Very refreshing.

 

thanks for the help that dont sound bad to do at all i just got to find the right stuff now. so there is no issues with running it the way it is i just wanted to double check. also i noticed the plugs in my truck are not recomender for the year but they are on 83 82 down 77 and so on. should i leave them in or go with what is listed they are also listed for every year down as well just 1 number hotter. curently has autolite 124 but calls for autolite 45 for my year. i think i might just see what the 45s do se if i can feel a diference. thanks for every thing so far though.

 

If you do the full DS2 conversion, go with plugs for the earlier years. With the TFI system, I'd say stick with what was originally meant for that system.
Driving it the way it is shouldn't be too harmfull, so long as the carb isn't way too rich. A very rich nixture can/will shorten the life of the pistons/rings/cyls, and can lead to premature bearing wear when excessively rich. Fuel can mix into the oil diluting it, so it no longer lubricates well.

 

He speaks the truth.
Check your spark plugs. If they're fouled, (black carbon deposits), you may be running too rich. Conversely, If they're white, or if the electrode seems to be melted (from pre-ignition), you may be running too lean.

 

Oh yeah, forgot to add, using the computer controlled TFI ignition with a non-feedback carb will keep the timing locked. This will hurt overall power and MPG by as much as 15-25%, but doesn't typically have negative effects on the lifespan of the engine, once the carb is adjusted as close as can be done without the timing advance giving the assistance it normally would.

 

Hey diesellou86,
Nothing more I can add except confirmation. This is all spot on.

The ignition system will run your truck, but at a loss of power and fuel mileage.

You have a 78 carb, so you shouldn't have any problems with it running rich (since that's usually a symptom of the feedback carb itself when the feedback components are on the fritz)

The only thing I will add to the description above of the Duraspark II ignition swap is that you can get all of the components from a mid 70s to 83. (Doesn't necessarily have to be 80 - 83). I'm not sure of the first year Duraspark II was used, but I've seen them as far back as 77/78. The only difference will be that on a pre-80, the ignition module is bolted to the fender, instead of the wheel well, but it's all the same.

Just be sure to have the ignition module checked out at a parts store, or just be safe and buy a new one. When I looked for one in a junk yard, I went through three bad ones before I gave up.

 

AB is correct about the DS2 coming into existance in the early 70's. It started showing up in most cars and some trucks thru 74, and by 75 it was pretty much standard on all fords.
One thing to watch for, if you extend your hunt beyond the 80-86 trucks. There are several variations of the system used thru the years. The wiring and module both had differences, and these were easily indentifiable by looking at the plastic insolator around the wires exiting the DS2 module. The setup you want/need will have a BLUE grommet. Make sure the harness and module both come from a vehicle that used the blue grommet module.
If you can find an 80-83 pickup, that has a 6cyl, that would be the best choice. The engine harness is a bit different for the 6cyl than the V8. Most notably, the oil pressure and water temp sender wires are different length, so a V8 harness *may* need modified to work on a 6cyl. This harness also contains the coil power connector, which could also have different length wires.