Jim Smart
September 17, 2012

When Ford was developing and racing its legendary 427 FE big-blocks back in the 1960s, it endured a tremendous learning curve that was proven out in dynamometer laboratories and racing venues worldwide. It was never easy for Ford to achieve this greatness because nothing worthwhile--especially in racing--has ever been easy. Burning the midnight oil, breaking prototype parts, and financing expenses are all key requirements for success. All of this was spurred by Henry Ford II's desire to hand Enzo Ferrari his jewels at Le Mans, the world's biggest motor racing stage. Not only did Ford do it once, it did it three consecutive times with exotic Ford GT40s. Ford proved it was dominant, global, and a force to be reckoned with.

The man that made Ford's will a reality, Carroll Shelby, is the subject of many stories and folklore. Prior to his involvement in the GT40 program, Carroll Shelby's objective was to design and build the world's fastest sports car--and he did in 1965. The 427ci Cobra went from 0 to 60 mph in 4.2 seconds, 0 to 100 mph in 10.2 seconds, and had a top speed of 160 mph. It tipped the scales at 2,350 pounds with more than 500 horsepower on tap. Shelby's 427-powered Cobra held the crown of world's fastest production car (0-100-0 mph in 13.2 seconds) for more than 30 years before Ferrari caught up and passed the Cobra a few years back. In competition dress, the Cobra was a Ferrari-spanking 580-horse powerhouse using real American V-8 twist. It was this formidable powerplant that Shelby also shoehorned into the GT40 Mark II to make it the race-winning machine that it eventually became.

Before you are two such 427s. One is vintage Cobra specification and the other a 482ci stroker. Both are custom built for McCluskey Limited of Torrance, California--known for its extraordinary Cobra rocket ships. The objective was to build and test a '66 Cobra specification 427 and wring it out on the dyno to see how it would perform. Aside from the rare C5AE-H Medium Riser aluminum “X” heads, magnesium intake manifold, and a 780-cfm competition Holley with Le Mans bowls, this is a period piece from the 1960s. We're talking aggressive flat tappet cam technology from Comp Cams and a stock Ford dual-point ignition with MSD assistance.

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Entrusted with the vintage hardware were Jim Grubbs and Jeff Latimer of JGM Performance Engineering. Both employ a wealth of engine building and tuning experience between them, which made it straightforward to build two 427 FE powerhouses that would leave indelible marks in the JGM dyno record books.

We actually kicked off this build in last month's issue, introducing the two-engine comparison. Block 1 was a genuine SOHC block with a casting number of C6AE-B, which doesn't mean “SOHC” but certainly a 427 side-oiler. What made it an SOHC block were the 5?8-inch oil drain holes at the rear of each deck, which got our Ford Blue blood pumping. Block 2 was a genuine vintage Cobra block with the original Shelby CSX VIN stamped in its iron. While Block 1 would be built, dyno tested, and placed on static display. Block 2 would be stroked to 482ci and raced in a Cobra Daytona Coupe.

There are elements that make the 427 side-oiler different than center/top-oilers. What stumped Latimer was the presence of a pressure relief valve in the block and in the high-volume oil pump. Strike up a conversation in any FE crowd and you will get a variety of opinions on what to do about oil pressure control in the side-oiler. Originally, the 427 side-oiler didn't have an oil pressure relief valve in the pump, but rather had one in the back of the block. JGM opted to remove the oil pump's relief valve, much as Ford did to begin with, and go with the side-oiler's gallery relief valve.

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