While I've driven ford trucks for years, they've all been relatively newer trucks (97 is the oldest). My youngest daughter (god bless her) wanted an old truck for her first vehicle. I found an 83 F100 for a great low price which I picked up.

She loves the truck, which seemed like a "good old truck" at the time. My concern now after having it around, is that it while its a good old truck from me, it's a bit rough around the edges for her as a starting driver.

Particularly around starting, idling, acceleration, etc. I'm pretty sure I can improve it from where it is with better tuning and fixing some other potential carb issues. But what I'm considering is just making the move to EFI so that it starts/runs more like a "modern" truck.

As I'm at the very beginning of this project, I'm open to just about anything. Don't want to break the bank, but am willing to sink a few grand into it if needed.

Should I be considering a throttle body type EFI to replace the existing 2barrel carb?

Swap the entire fuel system/engine control for a late model mustang unit?

Swap the entire engine for something else?

Thanks in advance for any input. I've tried googling these things and have started searching this forum, but haven't found anything that seems like a good answer yet.

Joe

 

Welcome to the forum, hortonjoew!

Since you are new and have too few posts to be able to send private messages, I will PM one of our forum members who is quite the believer that a properly tuned carburetor/choke will start just as quick if not quicker than a F.I. engine. He has a lot of experience and very kindly shares his knowledge. His forum name is Lariat 85. I will ask him to join in the discussion and help you.

 

In a properly tuned and running carb'ed vehicle, I see no reason to worry. If I were going to worry about something with a new driver, I'd concern my self with the advances in crash protection over the last 35 years waaay before the engine management technology. That said, I hope my kids can drive the '81 as their first car (They'd be the 4th generation of family to drive it).

My '81, starts, idles and runs without an issue with two exceptions. Just remember, pump the gas once to set the Automatic choke and don't floor it at low rpm for the first minute or two and it'll be fine. The weak point with mine is hot starts on hot days. It always starts, but not quite with the confidence you'd hope. Also, you need to give it a minute or two when cold before putting your foot into it at low RPM or it'll stumble.

As such, what what EFI gets you, in general, is a bit more of a point-and-shoot experience -- in otherwords it kinda lets you disregard what's going on under the hood a bit as the computer will just take care of business. So, EFI systems tend to be less temperamental when very cold and after a good heat-soak. You also get a system for which the a/f mixure is adjusted on demand for the particular conditions at hand, giving you a broader power band and better fuel efficiency, generally speaking.

I don't hesitate to let my Wife drive the '81 Ford or the '83 Rx-7. They're properly maintained and again, as long as you let the combustion process stabilize before taking off down the road and putting your foot deep into it, they drive just like any car. In some ways better because you get a nice linear throttle response, which you loose in a lot of modern throttle-by-wire setups.

 

While all of the safety issues are concern and something I debated. I finally gave in with the combination of her cautious driving style and the trucks solidity compared to a small modern car.

Thanks for the input. It sounds like the truck just needs more tuning that I thought. The previous owner had replaced the engine, and modified several things on it. But at this point, it'll run fine when warm, but if it's cold outside (think below 45) you have to let it set and idle for what seems like forever, probably pushing 10 minutes or more before it'll idle well enough to attempt driving without the risk of dying.

 

Properly tuned with ALL of the necessary components in place and functioning, a *stock* 1970s - 1980s carbureted vehicle can start and run just as good as any modern fuel-injected vehicle.

Stock vehicles during this time had the latest and greatest technology for carbureted systems. Specifically, these years utilized a thermostatic hot air choke and a temperature-controlled thermostatic air cleaner to improve driveability. These items are vastly superior to anything the aftermarket offers when it comes to street vehicles, and they absolutely need to be there if you want your carbureted truck to run as good as a modern fuel-injected vehicle.

Since carburetors don't have an engine computer to tell it what to do, they need the choke to mechanically enrich the fuel mixture when the engine is cold, and the thermostatic air cleaner to keep the incoming air at a consistent temperature for better driveability and to prevent carburetor icing. While the vehicle will run without these items, it will *not* run as good as a modern fuel-injected vehicle unless these are in place and functioning correctly. Most vehicles of this vintage are usually missing these very important items.

The *only* thing that is not going to be "modern" is the first initial start-up for the day. You have remind your daughter that she must push the accelerator pedal to the floor once before she cranks it to set the choke and to squirt fuel down the intake. Tuned properly, one or two pushes should be all that is required to start the engine, and not even that on a warm engine.

1. - One pump of the gas is normal to start a carbureted vehicle for the day.

2. - Having hot start issues is not. Is your truck all stock? If not, what carburetor are you running? And are you running the stock air cleaner or an aftermarket chrome job?

Aftermarket carburetors with an all-electric choke and lack of external fuel bowl vent(s) with an open-element air cleaner typically have this problem.

Stock carburetors with a thermostatic hot air choke and external bowl vent(s) topped with a thermostatic air cleaner do not.

Capiche?

 

It's definitely not stock. It's got one of the typical chrome air cleaners setting on top of the 2 barrel carb. Also, at some point, they hooked up a manual choke.

I've got a feeling this thing has been worked over pretty well. Am I more likely to find the correct replacement factory parts, or are their aftermarket items that would replace what you mention? How do I handle the items you mentioned if I go get a better intake and a 4barrel carb?

Also, this thing is find for putting around town, but extremely gutless at highway speeds and on takeoff. Not a huge problem for her going to school or a friends house, but I would feel better if it had a bit more power to be able to move if necessary.

 

From what you describe, I have the same feeling.

The replacement stock parts that you need are getting harder to find every year. Consider the newest truck of this vintage was 1986, and that was 30 years ago. Hardly any junkyards keep vehicles that old anymore.

The aftermarket does not offer a replacement carburetor with a thermostatic choke nor a thermostatic air cleaner.

What engine do you have? If you want your vehicle to run as good as a modern fuel-injected vehicle but with a four-barrel intake and carburetor, your only hope is to find a factory vehicle that had those items on it, and transfer them to your vehicle. Like I did.

That is because your truck is just like all the other smog-era vehicles of this vintage. Performance suffered because of tightening emissions standards. Your truck has big-chambered smog heads, an emissions cam that basically smothered the engine, and a small 2-barrel carburetor with a very restrictive exhaust system. Plus, it is now 35 years old and you have some missing parts. Who knows what else has been done to it over the years?

 

Mine is all stock. The issue was helped immensely be re-torquing the carb down onto the manifold. Another improvement was had by setting the ignition timing with a vacuum gauge, rather than to the factory timing marks. It's still not as good as I'd like. Cold it starts with basically a tap of the key. Hot, it cranks for a few seconds. When it catches, the idle is slow and rough for a minute.

Of course, I have other issues at this point which are impacting things. I'm soaking an aircleaner every 2K miles due to blow-by (Yes the PVC system is working) and the carb can barely hold a tune -- I'm actually quite pleased it runs as well as it does.

Sorry, didn't mean to hijack the thread.

 

Do you still have the hose that runs from the carburetor down to the charcoal canister hooked up?

If not, make sure the large nipple on the carburetor fuel bowl that the hose connects to left open. If you cap this off, the hot fuel vapors can only escape to the inside of the air cleaner. This results in an overly rich mixture when the vehicle is hot and you can get the symptoms you describe.

 

Thanks for all the input. So I from what you've said, I've got basically four options.

Tune it as it as best as possible and accept whatever it become.

Scrounge around junk yards and the internet to find the replacement factory parts to replace what is missing and improve drivability. Assuming I can determine exactly what has been done and it's even reversible.

Drop an aftermarket TBI on it and attempt to get it to work with what's already present. Speaking of which, did all trucks of this vintage have the AOD trans that requires special treatment and connectivity? How do I tell if it currently has that? (trans could have been swapped as well for all I know).

Rip/replace the entire engine (and likely trans). What would be a good donor to look for to minimize the amount of custom fabrication/work required?

Thanks again guys. Looks like I've got a nice body money pit for my daughter ;-)

Joe

 

Your daughter has to accept whatever it becomes. Don't forget that.

Good luck with that. Unless you are "one of us" and you are madly in love with your truck, this can become a total nightmare to figure out.

But you should still be able to get your truck to run fine. Maybe not as good as a modern vehicle with EFI, but aftermarket carburetors and a manual choke can still work very well.

You will know if you have an AOD if your truck has the following shift pattern marked inside the gauge cluster:

P R N OD 3 1 (1980-1981)
P R N OD D 1 (1982-1986)

If you have an AOD, it needs to be connected to the carburetor correctly or you will destroy it in very short order.

 

That sounds like carb icing. That temp is prime for ice buildup at the venturis.

You mentioned the stock air cleaner had been replaced by aftermarket. The stock unit had provisions for temp control, drawing warm air as needed from a shroud around the passenger side exhaust manifold. While that system's primary purpose was to provide a consistent intake temperature for mixture control, it also prevented carb icing. As mentioned, most junkyards won't have the air cleaner, but eBay should if you decide to go the stock route.

 

Something like this: Used 1985 Ford Pickup Truck Air Breather Cleaner V 8 | eBay

or this: 73 74 75 76 77 78 79 Ford Truck 78 79 Bronco 400 351M Air Cleaner Assembly | eBay can be made to work.

Ctubutis [moderator] has one on his truck which I believe he found on a full sized Mercury or Lincoln.

One more: http://www.ebay.com/itm/Ford-302-com...NW0z7W&vxp=mtr

 

I have a early 85 that still has that computer controlled carb and ignition system on a 302. The only thing that is not stock is the air cleaner assembly. My problem with it is when it's below 50 degrees the truck will start right up after 2 pumps and it won't stay running unless I throttle it for a while. Once I get it running steady at let's say 1,000 rpms, then the rpms will start dropping (even when my foot is in the same position that I had it for 1,000) then when it gets between 500-700 rpms it will suddenly it spike right back up to 1,000 rpms by its self. It will do that for around 5 minutes then suddenly it runs at 1,000 by itself perfectly fine. When it's all warmed up it runs perfect. I only ask because my dad has a 84 mustang LX with a 302 and all the factory dura spark components and he can just get up and leave with no problem. I hope that explanation of my problem made sense. Lariat 85 do you know what I can do to fix this? I noticed in your signature you put a duraspark setup on your 302.

 

These symptoms are text-book for a carb icing up, due to no longer having a hot-air intake system for cold starts.

The engine initially will run fine, then with the cold/damp air passing through the venturi ice forms & accumulates; this slows the idle down & also causes an overly rich mix.
Suddenly the ice breaks free & is sucked into the engine......now with the venturi clear, the mixture corrects; rpms lift & the cycle repeats until the engine has warmed the carb & intake enough to prevent the problem.