4 Cylinder To 5.0 Conversion - Mandatory Modifications

These are the absolute basics needed to complete a successful 4cyl to 5.0 conversion
  • First of all you will need a complete 5.0 engine with all accessories, the complete engine wiring harness and all the vacuum lines and bulbs.
  • The engine cross-members are the same in both the 4cyl and 5.0 mustangs but the 4cyls have motor mount adapters that bolt on to the cross-member. Remove them.

  • The 4cyl automatic transmission has to be replace with a 5.0 transmission (5.0 AOD, or a C4).The 4cyl and 5.0 T5's look almost identical and they both seem to fit but the very ends of the input shaft are different diameters as shown. I'm told that you can replace the pilot bearing with one out of a 1990 Mazda truck and the 4cyl transmission will work just fine. I have not tried this yet but I will someday.
  • If you are changing over from an automatic to a 5spd you will have to trim the hole for the shifter or it will hit the floor pan. You will also need to switch the pedal assembly to a clutch assembly. The speed-o cable will have to be re-routed because on an automatic it runs though the clutch cable hole. A 5spd double hump trans cross member, and drive shaft are also needed.
  • The trans cross-member for the 4cyl 5spd will work with 5.0 5spd as long as it is has two humps to clear the dual exhaust
  • The 4cyl radiator will work with the 5.0 I'm told (mine had a high flow radiator in it).
  • The 4cyl rear-end will drive with a 5.0 in front of it but for how long is up to someone else to find out
  • The 5.0 drive shaft will have to be used.
  • The complete length of 5.0 fuel line are needed and of course the fuel pump needs to be switched but the 4cyl tank its self and the fuel gauge components can be used.
  • The full length of brake lines should be switched but if you are careful you can get an adapter length of steel line to bring the brake line to the other side of the car where the 8.8 rear-end brake hose is. BE CAREFUL that the brake lines do not rub on the mufflers. (I learned this the hard way) I recommend to use the complete 5.0 brake lines.
  • If you do keep the brake lines running down the passenger side, you will have to modify the hanger for the passenger side muffler. (just grind a bit off)
  • If your 4cly is 86 or newer the holes for the quad shock come pre-drilled, so just use a battery terminal cleaner to clean out the holes.
  • The alternator wires have to be lengthened but they work other than that.
  • The 5.0 clutch and throttle cables need to be used
  • The main 5.0 vacuum distribution tree will have to be used.
  • The 4cyl power steering hose will work with the 5.0, just remove the switch from it and plug the hole with a pipe plug. The 5.0's come with an extra loop of solid power steering line for cooling so you probably want to use it.
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  • If you do keep the brake lines running down the passenger side, you will have to modify the hanger for the passenger side muffler. (just grind a bit off)
  • If your 4cly is 86 or newer the holes for the quad shock come pre-drilled, so just use a battery terminal cleaner to clean out the holes.
  • The alternator wires have to be lengthened but they work other than that.
  • The 5.0 clutch and throttle cables need to be used
  • The main 5.0 vacuum distribution tree will have to be used.
  • The 4cyl power steering hose will work with the 5.0, just remove the switch from it and plug the hole with a pipe plug. The 5.0's come with an extra loop of solid power steering line for cooling so you probably want to use it.

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