Mustangs from 1979 - 1995 Used a 5.0 L block, Which was Basically a 302 Windsor Block that was available back in 1968 Mustangs.
(In 1979 They added 5.0 To make it look more appealing.)
So truthfully 1968 - 1995 Marks the Exsistance of the 5.0 (302 W) Block in publically available Mustangs.
Fuel Injection started in 1985 for The Ford Mustang. The 5.0 Does have a Fuel line that goes straight into the engine (No return lines) In 1996 Ford Switched to a Smaller 4.6 L (281 CID) Block... The 2000 COBRA "R" MODEL (Notice the R at the end) used a 333 CID 5.4 L Cast Iron Windsor Block. (This is the same block used in the Current Ford SVT F150)
And to the guy that said a 199x - 200x Mustang can't handle a 5.4, They're wrong. Theres an issure of HOTROD magazine as well as the 1994 10L Boss Produced by SVT Team *only 10 in the world exsist*, (In which theres a 429 CID Engine) in each Mustang.. Check out
go to concept cars and check out the 10L boss... They did that without cutting and it fits right in, nothing needed to be moved around...
To the guy that started this trend, from my understanding your going to have to switch fuel pumps and fuel rails, the 4.6 Block that came from the 2000 COBRA (Notice its just cobra and not COBRA R) needs a return fuel line, it wasent made to burn the Excessive fuel that the 5.0 Needed. The Injectors would also have to be switched (Use the Injectors from the 4.6 with the 4.6, Because the 5.0 Used Higher Lb/Hr. Injectors then that of the 4.6)
I personally think it would be easier to swap a fuel tank from a 4.6 onto your 80's Mustang and swap the blocks, and that should settle all the Major problems you would experience... (You will also need to get your hands on a 4.6 ECU..)
If theres anything else Just reply here and hopefully I can keep up on this thread.
Mustangs are my Favorite car, Love em to death, I currently co-own a 1997 and am looking to buy a 94 - 95 GT for myself (Last years of the 5.0) Good luck and I hope this Helped others as well.
When I re-read your post I think you got the Engines mixed up man..
The 4.6 281 CID (used in the 2000 Cobra) uses a Fuel Return Line
The 5.0 302 CID (Used in your Friends 86 Mustang GT/LX, Etc.) Uses a Straight Line that fed into the engine and had NO FUEL RETURN line
Then theres a 2000 Cobra "R" which uses a 5.4 333 CID Engine, From what I recollect this as well diden't use a Fuel Return line.
I doubt you got your hands on a 2000 Cobra "R" because theres only 300 of those in the world and the selling price on one was marked at $54,000+ The Engine could have been ordered After market but You said your friend got The block out of a 2000 Cobra...
So that leads me to beleave you have your hands on a 2000 Cobra 4.6L (281) Block, and your friends origional 5.0 (302 W) blocks.
Remember as I said earlier, the 4.6 HAS and NEEDS the fuel return line to keep it from running RICH.
The 5.0 uses a NON Return line system (The Fuel pumps into the engine and stays there).
Thats why when you put the 86 5.0 Fuel rail on the 2000 4.6 Block The Engine ran RICH as hell, because it diden't have the Return fuel line the 4.6 Block NEEDS, to bleed off the un-needed fuel it was getting.
You might also want to check your FPR (Fuel pressure regulator) and make sure its not Set at a High pressure, or else your defeating yourself there as well....