Dale Amy
June 21, 2010

Without ceremony or fanfare, shortly before 1 p.m. on Monday, March 1, 2010, the final 4.6-liter Three-Valve Mustang engine trundled slowly down the overhead assembly trolley to the final inspection station at Ford's Romeo Engine Plant. Ever the Mustang romantics, we wanted to be there to document the official termination of this 15-year relationship between Pony and powerplant, one that may have had an iffy beginning, but which matured into something pretty strong over time.

We've been to the sprawling 2.2-million-square-foot Romeo plant before-it's in a rural area a few miles due north of Detroit-but previously only to its so-called "Niche Line," where the supercharged 5.4-liter Condor (GT500) and 4.6-liter Terminator (Cobra) Four-Valves have been lovingly bolted together in the relative calm of a dedicated facility. In comparison, Romeo's main high-volume line, where for the last few years all of FoMoCo's armada of Two- and Three-Valve 4.6s have been produced, is a noisy, immense, and incomprehensible multi-level maze of automated or manned machine tools and work stations, all joined by mechanized lines or overhead trolleys, and bathed in the Halloween-orange glow of what we presume is low-pressure sodium lighting. In short, this is the definition of a modern engine-production facility, efficiently transforming raw block castings into complete V-8s, needing only gasoline and the guiding electrons of a processor to make horsepower and smiles.

Anyway, grateful for the friendly cooperation of Romeo's employees and management, as well as Ford's PR team, we took what photos we could. But in the end, nothing could stand still for long because even though the last aluminum-block Mustang Three-Valve had been built on this day, armies of iron-block 4.6-liter variants continued to march down the line at a rate of somewhere around a thousand engines per eight-hour shift, headed for the likes of Crown Victorias, Explorers, and light-duty trucks.

Inside the plant, there was disappointment that production of the Mustang's new 5.0-liter Coyote V-8 had been assigned to the Essex engine plant, located across the Detroit River in Windsor, Ontario. But that loss is partially compensated by the fact that Romeo will build the big-bore 6.2-liter truck engines now appearing in '11 Raptor and Super Duty pickups. Sadly, we're assured the 6.2 is a bit large for the Mustang engine bay.

Horsepower Highlights
• 1996: Goodbye pushrods, hello overhead cams. The GT gets a 215hp SOHC Two-Valve 4.6, while the Cobra boasts 305 hp, DOHC, and four valves per cylinder. The GT's new modular was a silky-smooth operator, and claimed about the same horsepower and torque ratings as the outgoing 5.0 pushrod, but its reduced displacement could be perceived by a right foot, and the aftermarket was scared to death of its newfangled complexity. We were worried.

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