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  • “Project Six-Four” Part 2: Unlimited Diesel Performance Builds a 6.4L Ford from Scratch

“Project Six-Four” Part 2: Unlimited Diesel Performance Builds a 6.4L Ford from Scratch

Unlimited Potential

Todd Kaho
Feb 29, 2016
Photographers: Todd Kaho
In our first installment of this engine-build series (”Project Six-Four” Part 1: Unlimited Diesel Performance Builds a 6.4L Ford from Scratch), the rock-solid short-block of Unlimited Diesel Performance’s 6.4L Ford Power Stroke engine was complete and bolted to an engine stand, awaiting phase two of the build. Well, a lot has happened since then, and it’s all good.
But, before we get too far ahead of ourselves, we turn our attention to the completion of the long-block. Using fresh, new components is one of the build’s primary initiatives, and each part (even relatively simple things like the oil pan and oil pickup) is carefully scrutinized before installation to determine if there is a better, stronger, more reliable, or higher-performance alternative.
Preparation of the 6.4L’s cylinder heads is a good example of the attention to detail Nate devotes to the build process, and the first step is porting to provide better flow on both the intake and exhaust sides. However, there is a downfall with stock heads that Unlimited is very aware of and equally as diligent about fixing: They’re prone to developing cracks. To prevent this from occurring, hardened exhaust-valve seats are installed to keep heat away from the cast iron. Hardened seats also protect the valves and prevent cracking at the glow plug and injector bores. Special care to install the seats at the correct depth is taken, because going too far and getting into the nearby cooling passages can destroy a head.
Cracks at the head studs can also be a problem. To remedy this one, Unlimited installs Elite Diesel Engineering’s head studs. Since the studs are made of H-11 tool steel, they only need to be torqued to 195 ft-lb rather than 250 ft-lb when properly installed. Little things, like alleviating cooling problems by using the latest-generation thermostats, are also addressed. Unlimited also replaces the stock water pump with Bulletproof Diesel’s unit, which features a billet-aluminum impeller. The plastic impellers in stock pumps can cavitate from deflection or break completely. The cavitation causes an aluminum timing cover to erode or can put a pinhole in the cover, allowing coolant to enter the crankcase and mix with oil (and ruin engine bearings).
In our next segment, Unlimited installs a super-trick air intake and fuel system as we move closer to firing the mighty 6.4L.
Photo 2/27   |   001 Project 6 4 Pt2 Upper Pan
Long-block assembly for Project Six-Four begins with installation of the upper oil pan. The upper pan serves two purposes: It acts as a windage tray for the lower pan and also incorporates part of the oil-pickup tube. Unlimited’s co-owner, Nate Bailor, secures the pan’s fasteners with 115 in-lb of torque.
Photo 3/27   |   002 Project 6 4 Pt2 Oil Pickup
The modified oil-pickup tube allows for more oil flow to the low-pressure oil pump. The update opens the outer portion of the tube to provide access to the entire screen.
Photo 4/27   |   003 Project 6 4 Pt2 Oil Pan
A new River City Diesel aluminum oil pan is installed next. The pan helps dissipate heat from the oil faster than the factory steel oil pan is able to.
Photo 5/27   |   004 Project 6 4 Pt2 Torque
Like the upper pan, the RCD aluminum oil pan’s bolts are evenly torqued to 115 in-lb. In addition to improved performance, the trick aluminum pan simply looks cooler.
Photo 6/27   |   005 Project 6 4 Pt2 Timing Cover
Photo 7/27   |   006 Project 6 4 Pt2 Torque Timing Cover
At the front of the block, a new timing cover gasket and timing cover are installed. Once the cover is seated, bolts are evenly torqued to 23 ft-lb.
Photo 8/27   |   007 Project 6 4 Pt2 Rotate Block
Even without the heads, a 6.4L Ford engine assembly is already pretty heavy. Chaz Roth and Alex Fowler assist in rotating the engine for cylinder-head install, which can be done either before or after the timing cover is bolted on.
Photo 9/27   |   008 Project 6 4 Pt2 Valves
The intake and exhaust valves are coated with Ionbond coating to reduce friction in both the guide and seat locations in the cylinder heads.
Photo 10/27   |   009 Project 6 4 Pt2 Porting
Unlimited Diesel Performance ports the cylinder heads to maximize intake and exhaust airflow efficiency.
Photo 11/27   |   010 Project 6 4 Pt2 Valve Seats
Cracking is a pretty big issue for 6.4L Ford Power Stroke cylinder heads, and hardened exhaust-valve seats are installed as a preventative measure. The seats dissipate heat and prevent cracks from developing between valves and in glow plug and injector bores. Special care is taken to ensure the seats are installed correctly.
Photo 12/27   |   011 Project 6 4 Pt2 Valve Spring Install
Photo 13/27   |   012 Project 6 4 Pt2 Valve Springs Installed
A pneumatic spring compressor makes assembling the valvetrain easier. River City Diesel’s intake and exhaust valves are Unlimited’s preferred pieces.
Photo 14/27   |   013 Project 6 4 Pt2 ARP Thread Sealer
ARP thread sealer is used on the Elite Diesel Engineering head studs, to seal against leakage from the coolant passages. The 6.4L engine blocks are known for occasionally cracking near their lifter valleys from using too much torque when securing the cylinder heads.
Photo 15/27   |   014 Project 6 4 Pt2 Head Studs
Elite Diesel Engineering’s studs are made from H-11 tool steel and have higher tensile strength than other fasteners. While most head studs for 6.4Ls are torqued to 250 ft-lb, the EDE studs are a better choice since they are only torqued to 195 ft-lb (to prevent cracking). After Alex Fowler tightens the studs, he backs them out a quarter turn so there’s no unnecessary stress at the bottom of the threads. This also prevents cracking.
Photo 16/27   |   015 Project 6 4 Pt2 Head Installation
International head gaskets (an updated version of the originals) are placed over the studs before dropping the new heads on the block. This step is easier as a two-person operation.
Photo 17/27   |   016 Project 6 4 Pt2 Head Stud Nuts
The nuts for each stud are initially threaded on until they’re handtight. Notice how an Allen socket is used to prevent the stud from turning in the block.
Photo 18/27   |   017 Project 6 4 Pt2 Snug Head Nuts
A wrench is used next, before the torque sequence is started.
Photo 19/27   |   018 Project 6 4 Pt2 Torque Head Stud Nuts
Torquing the heads down is handled by using the standard pattern. Final torque on the Elite Diesel Engineering head studs is 195 ft-lb—much less than competitors’ head studs.
Photo 20/27   |   019 Project 6 4 Pt2 Thermostats
The latest-generation thermostats are installed. Early design thermostats are known to hyperextend and cause high pressure in the cooling system, which is blamed for several radiator leaks in early 6.4L engines.
Photo 21/27   |   020 Project 6 4 Pt2 Valve Clearance
Both heads are checked for valve recession before installation. Confirming there’s sufficient recession is critical, as it ensures there is no piston-to-valve contact, especially with larger camshaft designs.
Photo 22/27   |   021 Project 6 4 Pt2 Second Head
Photo 23/27   |   022 Project 6 4 Pt2 Push Rods
Unlimited Diesel Performance uses Smith Brothers’ pushrods to achieve maximum valve travel, so you don’t have to worry about bending under heavy stress from the valvesprings. These pushrods have a much heavier wall thickness than the stock pieces.
Photo 24/27   |   023 Project 6 4 Pt2 Rockers
The rocker arm assembly is carefully dropped over the valves and pushrods.
Photo 25/27   |   024 Project 6 4 Pt2 Rocker Arms
Photo 26/27   |   025 Project 6 4 Pt2 Torque Rockers
After checking alignment of the rocker arms on the valves and pushrods, the full assembly is snugged down before final torque of 45 ft-lb is applied.
Photo 27/27   |   026 Project 6 4 Pt2 Water Pump
Bulletproof Diesel’s billet water pump is installed last, completing the long-block.


Elite Diesel Engineering
Pueblo West, CO 81007
Swain Tech Coatings
Scottsville, NY 14546
Bulletproof Diesel
Mesa, AZ 85210
Unlimited Diesel Performance