Performance

For all the excitement of driving a musclecar or street rod fitted with a thundering, 427-cubic-inch, big-block V-8, there's something you ought to know—a small-block V-8 has the lightning strike. Legendary Cobra racers such as Bob Bondurant preferred the less weighty 351-cube Ford because it provided better balance on a road course. Even Carroll Shelby admitted that the only reason he used the behemoth 427 was because the Ford brass wanted to promote it.

Commonsensical
Given those facts, while performance purists may gripe, the reality for car builders is that a small-block crate engine is a smarter choice. Not necessarily the right one, but still a better a way to go from a practical standpoint. But what if you still have to have that big-block power? That's where a stroked small-block can make your decision a whole lot easier. By lengthening the stroke of the crankshaft (hence the term "stroked"), the swept volume of the cylinders, otherwise known as the engine's displacement, can be increased to big-block proportions.


As one example of this approach, we took a close look at Coast High Performance's 427 Cobra Classic crate engine. Despite the big-cube label, the engine starts out with a 351 Windsor small-block V-8 that's stroked and tweaked to produce in excess of 500 hp and 500 lb.-ft. of torque.

500-HP Package
To provide some more insider info, literally, we followed along at Coast with a buildup of this customized crate motor (base price is $9,499, well below that of a rare and pricey 437 FE engine). As shown here, each of these engines is hand-built and precision balanced, and then run on a test stand for 45 minutes. After checking for any leaks, Coast gives the valves a final adjustment and, after cool-down, the heads are re-torqued to spec. That way, when your Cobra Classic arrives, it's all coiled and ready for some lightning-quick strikes.

Resource
Coast High Performance, 310/784-2977, www.coasthigh.com


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In addition to a bunch of hardcore performance parts, this 427-cube small-block V-8 is fitted with all the dress-up goodies, including a Cobra air cleaner and valve covers. The available options are a chromed alternator and polished intake, heads, water pump and front cover.

To accommodate a range of valvetrains, this Probe piston comes with a relief area for intake valves in the "twisted wedge" heads. The flat, raised "quench" area squishes the air/fuel mixture in the combustion chamber. From there, the flame front flows into dished area for more complete combustion, since extra volume is needed to burn the remaining air/fuel mixture.

For the 427 Cobra Classic package, Coast uses Edelbrock's Victor Jr. high-flowing heads.

On this optional AFR head, marks from CNC machining indicate a better consistency in the size of the port and combustion chamber.

These different types of Probe pistons allow for a range of engine outputs. The dished-top or "reverse dome" (left) has a compression ratio (CR) of 9.5:1 or higher, depending on the cylinder heads used. It's ideal for street use on pump gas. The flat top (center) typically has 12.5:1 CR for bracket racing application. The domed type (right) is solely for high-horsepower race engines with a 14:1 or higher CR.

The bumpstick in the 427 Cobra Classic is a Crane hydraulic roller cam and lifters (intake/exhaust specs: .595/.605 248/256 (110).

As an option, customers can order Probe's 4340 H-beam with ARP bolts (far right). The I-beam type (left) is a more basic type, and the machined I-beam (center) is somewhat lighter, and comes standard with the 427 Cobra Classic package. In stroking the displacement to nearly 427 cubes, the rods slightly lengthened in order to clear the crankshaft counterweights.

The increased displacement comes mostly from Probe's forged-steel 4340 crankshaft. A stock 351 Windsor crankshaft has 3.500-inch stroke, while Coast's 427-cid Cobra engine has stroke of 4.170 inches. There's also a slight increase in the cylinder bore by .030 inches.

As an option, Coast offers port matching on the Edlebrock Victor Jr. intake, which basically consists of blending the passages, which removes casting flakes and any excess material for a smoother flow of the air/fuel mixture.

Holley's 850 cfm carburetor is the tried-and-true setup for the 427 Cobra Classic. Electronic Fuel Injection is optional.



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