F150 87 302 with efi swapped to an 84 carb 300

I have a free 87 f150 that needs a motor and is in much better shape than my 83(with an 85 straight 6). This things has floor boards and all the windows! Well i’ve done an engine swap before from an 85 to an 83 but I wanted to know if I would have issues change engines to an efi truck. Will the the tank fuel pump cause issues with the low pressure mechanical pump? DId ford gear the 302 differently? I guess I’ll need to change some exhaust stuff also? Oh and the new truck’s clutch pedal does not return it is a hydraulic clutch. I have only messed with the manual kind so any tips would save me a lot of trouble.


Swapping in an earlier engine can be a huge problem, if your truck has to pass an emissions inspection.

In my state, you would have to get a BAR referee involved. Swapping in a newer engine and emisssions equipment is permissible, but not vice versa

I don’t know what the rules . . . if any . . . are in your state

The fuel pump for efi is not compatible with a carb setup, as far as I know. yes, the pressures will be too high. You would be better off using the mechanical pump, or a low pressure electric unit specifically for carbs

In all honesty, it sounds like somewhat of a headache

Not only are you going to an older engine, but a different type of engine

I think you’re better off finding a good used correct year 302 for that 87 F150, if you intend to bring it back to life

My state doesn’t sniff anything before 93 so no worries with emissions. I’m going with the 300 because I have it already and it’s a good engine. Plus I am poor and couldn’t afford a used 302. Oh and regarding the fuel pump it’s my understanding that the ford uses two one in tank and another hp pump at the engine. Can I leave the tank pump and use the mechanical on the 300?

If the truck has 2 pumps the one in the tank should be a low pressure feed pump which supplies the externally mounted high pressure pump. The HP pump will have to go for sure with a carbureted engine.
The LP feed pump should move enough gas to supply a carburetor but I would suggest using the mechanically driven pump in conjunction with the LP pump.

Another issue you will face is the ignition system. The 87 truck should be a TFI model and an 84 carbed engine will be a Dura Spark. You will have to change the 300 to a TFI distributor or convert the truck to a Dura Spark. The latter would be easier and save you the headache of dealing with failed TFI modules.

The 300 is a good engine. I know people that have put hundreds of thousands of abused miles on those things and they keep on chugging.

One of them had blowby so bad that a buddy of mine had to wire the oil dipstick down to keep it in the dipstick tube.
Otherwise, every time he hit the throttle he would hear a thunk from the stick being blown out of the tube and hitting the hood. The stick would fall back into place until the next time the throttle was depressed…

I hadn’t considered the duraspark issue. Reusing the distributor and moving the duraspark module does seem better. As I recall it only has a few wires so hopefully it wouldn’t be too hard to move over. Thanks guys!


That’s good to hear that you don’t have to get the truck through an emissions inspection

Apparently, the in-tank pump is low pressure, and the external pump is high pressure. I’m talking about the setup for the 302

I would be inclined to use the straight 6’s fuel setup, and somehow transfer it to the 87 body. I don’t think you can get the mechanical pump to suck fuel out of the efi tank, not without modifications, because the mechanical pump would be trying to suck fuel THROUGH the in-tank pump

Drop in a different sending unit, without a pump, a unit that will fit the tank and fuel setup

Do both trucks use the same size and style fuel tank?

With style, I mean, where is it located . . . aft, midship, etc.

see where I’m headed with this?

The new truck has dual tanks not the old one but they both use that long skinny tank on the drivers side. My old truck tank is fairly new but the sending unit is shot. So I was hoping to use the new tank as is. Would .it be weird to run both pumps? Maybe with a pressure regulator?

One other thing is the motor mounts. Some folks seemed to think the existings mounts would work another the mounts needed to be moved forward a third the mounts needed to swapped from the 83 and a fourth thounght holes would needed to be drilled. Any insights?


I don’t think the existing V8 mounts would work for the straight 6

However, the 4.9 liter straight 6 was an option on the 1987 F150

Here’s an idea . . .

Get yourself motor mounts for the straight 6, for the 1987 model year F150. I’ll assume they bolt right up to your 1983 engine. There’s 4 years difference, but I’m assuming the 1983 engine will accommodate 1987. Hopefully, they’ll also bolt up to the frame/crossmember in a location that will work for you

The mounts have to fit the truck, also. That is why I suggested getting mounts for a 1987 F150 with the 4.9 liter straight 6

I just looked on rockauto and the straight 6 mounts are NOT the same, 1983, versus 1987. The 1987 was a newer body style than the 1983. That is probably why the parts are different

Motor mounts are cheap, and I would buy new ones. Your old mounts are probably shot anyways

That’s a great idea about the motor mounts. I’ve been looking at the wiring diagram for the 87 and it’s pretty intimidating to think of splicing in the duraspark icm.