Ford has had dozens of blocks over the years, made either from aluminum or iron. Five plants have made blocks for the modular engine: Romeo, Windsor, Essex, Teksid (Italy), and Cleveland, which manufactured the Boss. Between these engines not much interchanges. Some high-performance builders favor certain blocks, but in general all the blocks are very good, strong pieces. What you have will probably work fine.
All modular engine cylinder heads are made from aluminum and come in three basic configurations: a single overhead cam (SOHC) with two valves per cylinder, an SOHC with three valves per cylinder (two intake, one exhaust), and a dual overhead cam (DOHC) with four valves per cylinder. Ford has changed the intake ports and exhaust configuration frequently through the years, making it difficult to swap cylinder heads on these engines. Ford made some improvements in 1999 and introduced the PI head, which stood for “Performance Improved,” not “Police Interceptor” as older engines were designated. Early heads are referred to as NPI or Non-Performance Improved. Early 4V heads had dual ports, which was changed to a single port in 1999. SOHC and Coyote engines have round exhaust ports, and Cobra and other 4V heads were oval.
All modular engine heads are made from aluminum. The oval exhaust port on this head identifies it as a pre-Coyote 4V DOHC head. Note the added chain to run the second cam, the center-mounted spark plug, and the use of cam followers and valve-lash adjusters.
Crankshafts come in 6-bolt and 8-bolt configurations. The 6-bolt crankshafts were made at the Windsor plant, and the 6- and 8-bolts cranks were used at Romeo. Some special crankshafts were made, such as the forged-steel crank first used in the 2003 supercharged Cobra engines. A lot of performance parts, such as flywheels and clutches, favor the 8-bolt crankshaft.
In 2016 Ford introduced the new flat plane crankshaft for the 5.2 Voodoo engine. The firing order is different from all the other modular engines and gives the engine a unique sound.
Ford turned the performance world on its head with the 2016 5.2 flat plane crankshaft. The flat plane crank allows the engine to fire left right bank evenly, different than normal V-8 engines. This allows for better exhaust scavenging than traditional V-8s. Weight savings is due to not having additional counterweights. Firing order on most modular engines is 1-5-4-8-6-3-7-2, and the 5.2 is 1-5-4-8-3-7-2-6. (Photo Courtesy Ford Performance Parts)
Valvecover ID
The type of valvecover on a modular engine provides a quick identification. In this brief sidebar, the various styles of valvecovers are shown and described to provide a quick and easy indication of the particular engine. To verify the year, factory of origin, and type of modular engine, refer to the engine ID tag.
The 4.6 Romeo two-valve valvecover is a composite cover and has 11 bolts holding it to the head. Like all modular valvecovers it cannot be swapped left to right due to the timing chain and gear bulge in the front of the cover.
This typical early four-cam valvecover is painted black on this Shelby 5.4 engine. The silver center plate covers the four coil packs mounted over each cylinder. Earlier coil pack engines had a similar cover over the spark plugs and wires. The coil pack wiring exits the back of the cover.
The 4.6 Windsor-built 2V engines have a 14-bolt valvecover that cannot be interchanged with Romeo 2V valvecovers. (Photo Courtesy Jim Smart)
The 4.6 and 5.4 3V engines featured scalloped valvecovers to help with the relocation of the coils. The VCT (variable cam timing) system mounts in the front of the cover. These covers came in 10-bolt and 14-bolt designs.
The Coyote 4V engines have a much shallower valvecover and the wiring exits up and over the top of the cover to be hidden by the intake cover. The dual TC-VCT plugs can be seen in the front of the cover. The coil cover is aluminum and interchangeable.
Most crankshafts are cast nodular iron and have six or eight bolts to hold the flywheel/flexplate, depending on application and plant. Most performance aftermarket companies design parts for the stronger eight-bolt crankshaft design. When Ford came out with the 2003 Cobra, it opted for a forged steel crank to handle the supercharged engine. Forged steel cranks then started making their way into other production engines.
The intakes vary depending on application. Triton or Ford truck intakes tend to be taller with smaller, longer runners, whereas cars such as the Ford Mustang have the shortest intakes for clearance.
One of the early problems with the intake was a cracking condition with the new nylon designed intake manifold. The intake would crack along the front coolant crossover and the fitting ports would pull out.
Ford solved the problem with these 4.6 intakes by changing the design to include an aluminum crossover tube in 2002. This remained on the 4.6 production engines through the end. The design for later engines was improved and the intakes became all composite again.
Ford used multiple intake port designs on the modular engine, so swapping among different engines is very difficult. Ford had a factory recall late in the 1990s when a problem occurred with the all-nylon intake manifolds; the fix was an aluminum coolant crossover, which carried on through production in the early 2000s.
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