5.0 EFI Swap!

The gas station rebuilt 302 that the previous owner had installed was basically a piece of junk.  One cylinder was low on compression, and the engine didn't feel like it was balanced at all.  After living with it for 4 years, I decided to replace it with a later model 5.0 with EFI.  The engine swap is fairly straightforward.  The most complicated part of the swap was the wiring.  To keep the cost down, I chose to modify the donor harness instead of buying one made for the conversion.  A complete wiring diagram is a must if you plan on doing the wiring yourself.

What's Involved???

Engine: The 5.0 block is the same size as the early 289/302 blocks.  The old engine mounts work, as do your headers.  It is a 6 bolt block, so be sure you've got a 6 bolt tranny, not one of the earlier 5 bolt ones.  I previously installed a late model T-5 tranny, so I was set.  The flywheel on the 5.0 is larger, so you won't be able to use the old clutch.  I didn't use the power steering pump, and also deleted the smog pump as smog isn't required in California.  If you delete the smog system you'll need to plug two holes in the back of the heads.  Ford sells the plugs, but you can use two 1" long 5/8-11 bolts for 1/10 the cost.  The holes probably won't look threaded when you remove the smog tubes, but clean out all the carbon deposits, and you'll find that these bolts will work.

Belts: I chose to use all the late model accessories and the serpentine belt.  I measured the belt length and found the proper size at the local auto parts store.  If you're using A/C and an alternator without under drive pulleys, the belt length is 70.5".

Hoses: I used a 1990 Mustang upper radiator hose, and cut out a small section in the straight section for a Tefba filter.  For the lower hose, I needed a slightly different bend and diameter than the old hose, so I walked the aisle at the auto parts store and found one that worked.

Lower Hose

Upper Hose with Tefba Filter

Fuel: EFI engines require more fuel pressure than carbed engines, so you can't use the old fuel pump.  They also need to have a return fuel line plumbed back to the tank.  I tried a few different aftermarket fuel pumps, but they were all very noisy.  I used an OEM fuel pump from an 85-89 Merkur XR4Ti with a 2.3L EFI turbo engine from the junk yard..  Since it was from an EFI car, it was rated at a high enough pressure.  This pump is super quiet and works great.  I even tried the auto parts store replacement for this pump, and it was noisy.  Try to find an OEM pump (its a Bosch pump) and get the insulated bracket that holds it as well.
       I ran new fuel line from the tank to the fuel rail, as well as a new return line back to the tank.  It follows a similar routing as the old line, except they're on the passenger side where the bottom of the fuel rails are.  To plumb the return line into the tank, I drilled a hole in the fuel sender flange (off the car of course!), and silver soldered the tube in place.  Be sure use EFI rated fuel line and EFI hose clamps.

Throttle Pedal: The early Mustang throttle linkage is a lever/pushrod setup on the drivers side of the intake.   The 5.0 intake manifold is setup for a cable on the passenger side of the intake.  The easiest thing to do is to swap out the early Mustang pedal and linkage for the late model gas pedal and cable.  The pedal will need to be mounted on a spacer block, or you can cut, bend, and weld the pedal to give enough throw on the throttle cable.

Air Filter / MAF: The 90 Mustang mass air meter is mounted on a steel bracket.  I was able to use this bracket and mounted it to the front of the shock tower.  I used a K&N air filter which just barely clears the alternator.

O2 Sensors: You'll need to weld some O2 sensor bungs in your exhaust for the engine to run correctly.  You can buy bungs specifically made for O2 sensors for about $15, or make some yourself using some $3 parts from the auto parts store.  You'll need two 18mm spark plug anti-foulers.  You'll need to cut the ends off, then weld them in place.  If you've got long tube headers, they should be welded into the header right after the collector.  If you've got shorties, weld them into the exhaust tube, as close to your headers as possible.  When you weld them on, be sure the exhaust flange is above the bung, because it won't slide over it once its welded.  Guess how I found this out?  The left picture is from the UltraStang website showing how to modify the anti-fouler and weld it in place.  The middle picture shows one anti-fouler cut down, and one before cutting.  The right picture shows where I welded the anti-fouler on with the O2 sensor installled.

Performance

I Love It!!  The old engine was an early 80's truck engine, and the horsepower was probably around 130hp.  The 1990 Mustang 5.0 is rated at 225hp, and feels just super.  It starts instantly, and I'm getting 20mpg on the freeway.

EFI Swap Links

The following links I found useful when doing my swap:

http://www.mustangsplus.com/tech/efi/
http://www.ford-trucks.com/articles/5liter.php
http://www.acc-electronics.com/cloud/tc_auto.html
http://www.centuryperformance.com/fuel.asp
http://users.ev1.net/~gbuzek/index.htm
http://www.geocities.com/mstngmtt/Mustang/mustang.htm
http://www.painlessperformance.com/manuals/90518m/90518mhome.htm#startmanual
http://www.ronmorrisperformance.com/06tech/index.html

Last Update: 08/31/2003