Engine swap ideas

[84FS460]

I have a 86 F250 with a 5.0 EFI and a granny gear 4spd. The engine has 186,000 miles and getting a little tired. I have to go up hills in 3rd gear at high rpm. I would like to either rebuild the 5.0 with a little more horsepower or swap the engine out to maybe a 5.8 without changing any wiring and keeping the ECM. Or would I save money by just selling it and buying one with a different engine. Anybody have ideas or opinions?

[mat in tn]

oh, there are ideas! i build 5.0/5.8 all the time. one of each in the bay now.
you have the fuel injected 5.0 like the f150 or is it carbureted?

[Gary Lewis]

The EFI system you have is very limiting.  It is called "Speed Density" because it doesn't have a mass air-flow meter.  Instead, it assumes you haven't changed the cam, intake, valves, exhaust, or bore & stroke.  But if you do change very much you'll be outside of its ability to adjust and the engine will NOT run correctly.

So, you are fairly well stuck with stock, or close to stock, if you keep the EFI system.  There are folks that know just how much you can change and get it to work, but I know for sure you can't put a 5.8L in there and get it to run correctly.  And I doubt you can do enough else to get enough more power to make it what you want.

But let's see what the others say.  I really don't know how far you can push the EEC-IV system with changes and get it to run correctly.  However, my nephew had someone bring a system like yours to him recently and he discovered they'd made a number of "upgrades" that caused the computer to not be able to run the engine properly.  So he converted it to mass air-flow and got it running "OK".  But never could get it to run really correctly.

So, I'm thinking you'll be better served selling it and getting what you want.  But maybe you should tell us what you really want?

[Pete Whitstone]

If some downtime for the truck is acceptable, you won't get off cheaper than pulling the engine and rebuilding it yourself.

If you are interested in a bit more power, adding a stroker kit and some aluminum heads and a cam would be a good idea. I know that sounds like it's adding a lot of money but it's really not. Take heads for example. When you add up the cost of rebuilding an iron head (new springs, valves, guides, seals, the machine work, etc.) you are not that far off the cost of a new aluminum head with all that stuff already done.

Same for the stroker kit. You will most likely overbore your cylinders, so new pistons will be needed. Connecting rods rebuilt, crank turned under, all those costs add up and all those parts are included new in a stroker kit for not that much more. A kit to turn a 302 into a 347 is, again, not that much more. Here is a kit from Summit for $855.

https://www.summitracing.com/parts/sdm-pce290-1121?seid=srese1&gclid=CjwKCAiA78aNBhAlEiwA7B76py0MyELAIhN2VNI-w_BAMLCz2b-kPUlqN8Tiiw45fjGkKqLer2VJfRoCjs8QAvD_BwE

Then the other thing I would address is cam. With today's low-zinc oils, keeping a flat tappet cam alive is becoming increasingly more difficult. Switching to a hydraulic roller would sidestep that issue. This is an extra expense with the engine build, but one that would be worth it in my opinion.

If you can't have the truck down for the amount of time it takes to rebuild the engine, then see if you can locate a 94-96 5.8 in a junkyard and rebuild it. They came from the factory with hydraulic roller cams.

I say all this not really knowing your level of mechanical expertise. If you are not comfortable building an engine yourself, then maybe shop crate motors. It will definitely be more expensive than DIY, probably by about double. I have looked at this and there are some nice deals out there.

[Pete Whitstone]

Excellent points about the limitations of the stock EFI, Gary. That was something I had not considered.

Maybe throw a Sniper upgrade at it as well?

[mat in tn]

i just picked up on this. you said efi. im just getting started haha.
on these that is not really a lot of miles for the whole of the engine.is it possibly 280k?
if you personally have noticed a loss in power rather then it being new to you and just unimpressed, I would look at maintenance and tuning long before calling it rebuild time. i put 408k on a 5.0 in a 1/2-ton e150 van while it was loa........ded with tools and never pulled a head or even needed to change an injector. I did this with regular maintenance and one "additional" service. i replaced the timing chain at 150k then again at 300k. many said i was wasting time and money but most who were vocal were also commenting on their 400-dollar payments. friends and family who complained about me over doing things still called any time they wanted something done right.
seriously noticing loss of power is very commonly a clogged fuel filter. in which case its most likely clogged with water. efi uses a water separator type filter which has constant circulation so its not so much the miles or the gallons of gas but the tank condensation it there to pull out.

[85lebaront2]

One of the big issues is the 1985/86 5.0L EFI system is different in many ways so a later computer will plug in, but not run correctly. The EGR control system was only used in 1985/86. The engine its self has the worst heads Ford ever used on the small Windsors (221-302) with the exception of the 255 engine used in cars. As far as fitting things, Ford relocated the air filter to the left inner fender in 1987 and all EFI engines 1987-1996/7 have it there. The later bracket can be adapted to the 1985/86 fender, and Gary Lewis has done it and documented the method. The other 1987 change was the EEC location, it was moved down into a recess in the left cowl next to the driver's footwell and the EEC power and fuel pump relays were moved underhood on the back side of the air cleaner bracket.

Since your truck is a manual transmission model, essentially a Mustang 5.0L for a 5 speed along with it's wiring, sensors and EEC can be "dropped in". For a strong package without going to a 351, a later Explorer 5.0L has some of the best heads (GT40 or GT40P), but horrible exhaust headers to clear the body. These are a DIS system, but will accept a normal distributor.

Starting with the 1994 model year, Ford went to a roller cam on the 5.0L, MAF/SEFI injection and changed the firing order. The early wiring harness will not work correctly in stock form, but there are kits available to upgrade or convert to later systems, or the harness can be redone to a later configuration by moving wires around in the EEC 60 way connector and adding a few if needed.

[mat in tn]

very much a system i have used many times. i second the gtp idea and try to keep a set on hand. the exhaust manifolds are unique and its best to be willing to work with them as opposed to using headers in all but performance situations. custom y pipe or exhaust will be necessary. The 1986 heads were a one-year attempt at high swirl combustion chambers in the mustangs and thunderbirds (not entirely certain on the f150 efi) as i have seen e5 heads on them also. when ford discontinues something in one year, that's a clue.

[RenoHuskerDu]

Pete Whitstone wrote

Excellent points about the limitations of the stock EFI, Gary. That was something I had not considered.

Maybe throw a Sniper upgrade at it as well?

Gary's spot on. That old injection system uses only rudimentary realtime info, relies heavily on pre-stored maps to manage how much fuel to inject. Very limited.  I'd rather run a carb, but then you will need to run ethanol-free fuel. That's not too hard in Texas but other states may vary.

A Sniper is the bee's knees, but spendy. Several guys out here run them, iirc.  Some day I may go that route.

The 351W is a torquey option. There's a local guy who swapped a Mustang 5.0 in an F150, back when that made 250 honest HP. Of course he also installed the fuel injection and ignition. One of my sons is bargaining to purchase that truck, which has a broken frame rail from our rough terrain around here.