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  1. #1

    Default 84 tbird - 3.8 CFI to PFI swap

    Hi, has anyone done this swap? Thinking about trying to get 88 3.8 heads, intake and putting on CFI motor. Ive learned that the PFI was batch injection so it seems that ECM is fine. Any thoughts?


  2. #2
    FEP Super Member xctasy's Avatar
    Join Date
    Jun 2012
    Dunedin 9011, New Zealand, South Pacific


    Not sure which state your in.

    I would totally avoid any Fox 3.8, and find a smashed OBDII 1994/1995 SN95 engine and figure out how to run it on better heads.

    Focus only on the 1994-2000 engine because it yields a stronger block and better heads and induction, which make it a better platform for development. It has a trouble free EECV control unit, with only a few extra things to hook up.

    If its an IM inspection state your in, go 5.0. Or 2.3. Each is a rock solid base. The 3.8, not at all like those two.

    If using a stock numbers match block is your present need, then you can rebuild the basic engine, and then start over with the other mods. The variances with the Essex V6 were huge. Ford eventually changed everything, roller cam, balance shaft, reworked heads, block and crank to eliminate problems, and accommodate manual gearboxes...

    Any modified Essex V6 won't be responsive to the changes for every dollar like a 5.0 and the basic engine is missing out in the extra 12 years of really good fine fettle work Ford put into it for 1999.

    FB71 is the guy to talk to about this great little engine. I refuse to bad mouth an engine that "generally" made good horsepower, "generally" drank moderate amounts of gas, and was "generally" the staple go to six for every mid size Ford from 1983 to 2008 or so, plus some SUV's like the F150.

    Quote Originally Posted by FB71 View Post
    single port 3.8L heads are terrible. I have literally replaced or machined hundreds of them for warpage and cracks. I nearly paid for my first house with 3.8L head gasket and AXODE transmission recalls and repairs. The '99-up split port heads are far superior in durability, but don't interchange (easily) with the '98-prior single port heads. Pull the heads, have them checked for flatness, cracks and valve leakage. You will regret not doing that, if you just reassemble with new gaskets. Also, the 3.8s have a pretty sensitive bottom end. Any coolant in the oil quickly destroys bearing and journals, faster than most other engines, for some reason. It might be time to retire the ol' gal...
    plstktnkr2 has a great 3.8 Supercharged V6 using the better Supercharged parts.

    Somewhere, you have to consider the status of the "pizza base".

    The 3.8 is an engine that you have to really be careful with.

    Because the base is not very reliable, it needs careful consideration before sinking anything at all $$$ wise into it.

    Later model twin port heads are exceptionally good, even a 94-95 EECV V6 with better heads swapped in.

    The issue with any pre 1998 engine combination of 3.8 is

    a) lack of Rockwell hardness in the both the aluminum head castings
    b) bolt stud oxidization,
    c) water pump
    d) EGR blockage
    e) the possibility of main bearing degradation to consider.

    The Essex 90 is just not as inherently reliable as a 1998 on wards model year engine.

    The Port EFi swap is a good idea, it's just that the heads have to pass the Rockwell hardness test. The 1988 EECIV is an easy swap. But so to is another SN95 that hasen't been trashed.

    Re-read Jim Smarts "Advertorial" Super Six Motorsports article below

  3. #3


    Thanks alot! My 84 3.8 is just fine at the moment 73K miles. I have quite a fondness for these motors, as I had 2 of them as a teenager, and had both motors apart at one time or another. Both had rod knocks before 100K and needed heads, but they were fun to learn on. Is it a major ordeal to swap a 99 motor into a fox?

  4. #4


    Could i have my cfi heads drilled for injectors?

  5. #5


    Do you mean like direct injection? Sounds expensive and complicated.

    Otherwise you would want to inject near the transition from intake to head in the intake like the 5.0 and other period engines.

  6. #6


    Quote Originally Posted by erratic50 View Post
    Do you mean like direct injection? Sounds expensive and complicated.

    Otherwise you would want to inject near the transition from intake to head in the intake like the 5.0 and other period engines.
    no just to achieve injector placement as in 1988 heads at intake valve.

  7. #7
    FEP Member
    Join Date
    Dec 2016
    Grand Rapids, MI


    Quote Originally Posted by Atengnr View Post
    Could i have my cfi heads drilled for injectors?
    I don't think it would be worth the hassle. You could most likely find a good set of MPFI 3.8 heads for the same or less than what it would cost to modify the CFI heads. I'm going in a different direction with the 3.8 in my car, but I think the route you are going will yield excellent results. Driveability, reliability, and servicability should all increase exponentially. I've never had any issues with the 3.8 MPFI system in any of my cars.

    I have no experience with the split port engines (started in the '96 Windstar and later the '99 Mustang). I'm sure it runs fine as well, but the MPFI always seemed like a relatively simple swap on these engines.

    Make sure your heads are flat and have the proper surface finish for the head gaskets you use. I've always just used the regular Fel-Pro replacement gaskets and I've never had a problem.
    '89 XR-7 5 Speed
    '95 SC 5 Speed
    '91 Crown Vic P72 351W
    '95 Saturn SW2
    '85 Ford LTD Squire

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