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Purpose – why build a DOHC 5.4?
    When asked why I'm building a DOHC 5.4...I have an answer, though long and exhaustive, I do have an answer.  It all started when I found a DOHC 4.6 out of a 95 Lincoln Mark VIII on the Corral.net  auction block.  This was a deal that I just couldn't pass up. It was the whole drivetrain, motor, transmission (4R70W, the wide ratio version of the AOD-E, for more details see Baumann Engineering for details on this tranny), and rear end, for $1500 bucks.  This was less than a pair of new SVO heads would cost to put on my GT.  So I thought, hey, I can get this 4.6 DOHC and drop it in my GT.  The Lincoln motor came from the factory with 280 hp with single exhaust.  I figured I could get it up near the 305 hp the cobra's come with pretty easy.

    Once I decided to buy it, I had to get it to Houston from Miami.  This was just the beginning of the progression of expense.  It cost me nearly $400 bucks to ship it.  OUCH  I figured I could make up most of that by selling the tranny and rear end.  Well, the rear end sold pretty quickly.  It went to a guy wanting to put that (nearly) all aluminum rear end into a T-Bird, replacing it's heavier steel unit.  I still have that transmission, so if  you are interested, email me. :)

    Back to the history of my going for the gusto.   Once, I got the motor into the garage, I realized that this was going to be a bigger project than I had anticipated.  When I started disassembling it, removing the intake, valve covers, heads, etc. I found some problems.  First, since the throttle body on the Lincoln intake was at the back of the engine, a lot of complex plumbing would be required to make it work in my GT.  Then the real problem reared its ugly head.  The engine came out of a wrecked  Mark 8, and apparently during the accident, it caused some trauma to the engine.  The intake valves on the #1 & #2 cylinder had tagged the pistons and the exhaust valves had tagged the #5 & 6 pistons.

This caused me to rethink my decision to simply drop that little 4.6 into my GT.  It was at this point I started reserching the possibility of using a 5.4 short block.  Since Ford is putting a DOHC 5.4 in the Navigator, I knew that parts were available to put togther this beast.

    I then contacted Randy Stinchcomb in the Parts Department at Universal Ford in Baltimore, Maryland.  Randy is a friend of the Modular community and was instrumental in getting me the parts I needed.  He was also very helpful in cross referencing the parts to make sure that everything would fit.
    Now, this would do for a 'stock' type 5.4, but since I was going down this path, I didn't want to trash a motor because of weak pistons or rods.  This led me to my next bit of Engineering.
   
    The final major issue dealing with putting this engine together is the intake manifold.  A DOHC 5.4 intake is available for the Navigator, but unless I want a 8" cowl hood, I'd have to come up with a better solution.  Therefore, I am going to modify the Lincoln intake to fit the wider block of the 5.4, complete with a new GT style throttle body (this would make hooking up my existing components easier.)
    Currently, I am awaiting delivery of the remaining components I've ordered.  Rods, Pistons, head gaskets, etc. are all on the way.

Technical – Design Considerations

• Block-a new 5.4 truck block straight from Ford will be used.  This is the same block used in all truck motors, including (according to Ford) the Lightning and the Navigator.
• Heads-The heads are off a 95 Lincoln Mark VIII DOHC 4.6.
• Pistons-Standard forged pieces for a 4.6/5.4L from Probe Industries.
• Connecting Rods-Manley H-beam rods for a 5.4L Ford
• Crankshaft-5.4 truck crank, forged steel.

    Cams-Intake cams for a 96-98 Cobra will be used.  Exhaust cams are the same between the Lincoln & Cobra.
    Intake/Fuel System-The intake manifold from the Lincoln will be modified to fit the wider 5.4 block.  The original plenum and throttle body will be removed.  Primary runners will be left original length, while the secondary runners will be shortened to about 3-4" terminating into the wall of the plenum which will be constructed to encompass the runners in similar fasion to the Cobra intake.  A GT throttle body and 90 with EGR hookup will be mounted on top of the plenum.

        IMRC plates will be used to make the most of the dual runner length intake manifold.  Electric solenoids and an MSD rpm widow switch will be used to control the IMRC's in lue of the EEC (like on the Cobras.)

       Engine Control System-The stock GT EEC will be used.  All of the GT sensors are compatible with the new motor.  However, the knock sensors (stock on all DOHC's) will not be used since there is no provision for them with the GT EEC.  30# Injectors will be calibrated with a C&L MAF (with the appropriate sample tube.)
Machine/Welding Work
    Heads-DOHC 4.6 heads off a 95 Lincoln MarkVIII are used.  But considerable work needs to be done to them before istallation.
    Port & Polish work:
    Exhaust Ports were the first to receive a good cleanup.  Since I had NO experience on porting & polishing heads, I decided to start with the least critical area.  My goal was not to enlarge the ports (on neither the exhaust nor the intakes) but to just clean them up, i.e. remove the casting roughness, sharp edges, and abrupt changes in geometry.  In fact, I did not even remove enough material to completely remove all casting traces.

Primary Intake Ports, Before and After
Note: the port is NOT bigger, it only looks that way due to the camera angle and zoom level.
The important thing to notice is the surface finish of the ports, i.e. lack of casting roughness.

Secondary Intake Ports, Before and After
also note the valves are still on the 'before' pics.

Combustion Chamber:  All I did in the combustio chambe was remove the shrouding around the primary intake valve.

    Crankshaft-The crankshaft will be balanced.
    Intake Manifold-The Intake Manifold will be modified as described above. But, I will document it in more detail as I get the work done.
Assembly-Assembly will commence sometime in February 2000, with project completion (installation of motor into my car) sometime in February or March 2000.
Testing
Results

Parts List