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Engine Choices

In this edition I’d like to explore the various engine options available in your HAYDEN COBRA. There are different views on which engines to fit, and most choices, like the Cobras, are unique and customized to the taste of the owner. We do offer any number of options for your Cobra and are glad to assist you with advice and options.



A whole universe of engines can be fitted to a Cobra replica, and this includes the trusty original Ford Windsor and FE engines as well as the Ford Cleveland and Lima power-plants. While some purists maintain that a Cobra replica should be faithful to an original Cobra and house a Ford Windsor small-block or an FE big-block engine, the hobby has embraced all makes and models of V-8 engines. In fact, some are installing GM LS series engines into their Cobra because of the compact design, high-performance capabilities, massive aftermarket support, and ease of installation. While this may be sacrilegious for some, these combinations are becoming more popular.


Your choice of engine should hinge on several factors, including horsepower and torque targets (i.e., your ideal powerband), budget, and of course personal preference. Many Cobra owners opt for crate engines for simplicity, convenience, and reliable performance. Many companies can deliver a turnkey engine to your residence. After all, you’re assembling an entire car, and many do not want to build an entire engine from the block up.


Small-Block or Big-Block?

When it comes to powering your Hayden Cobra, you must ask yourself, how much is enough? What kind of handling characteristics are you seeking and how does the engine selection factor into that choice? Hayden Cobra replicas have a curb weight of about 1 200kg (2 000 pounds). Therefore, the car is extremely light and has a power-to-weight ratio that few cars can match.


For example, a HAYDEN COBRA with a 350-hp Ford 302 H/O small-block can propel the car to 240 kmh (150mph), and that’s just the tip of the iceberg, a high-performance 427-ci stroker smallblock can reliably produce more than 600 hp and put the Cobra’s performance into the stratosphere of supercar performance.


If you opt for a big-block you’re taking on much more weight, but you can easily build an 800-hp engine. Typically, most aluminum big-blocks weigh around 100kg (150 pounds) more than a small-block from the same manufacturer. Adding more weight to the front of the car degrades handling characteristics, and therefore it is less agile through corners.

Whether you choose a small- or big-block engine, you need one set up for your application. Hence, the powerband of the engine must match the application. If your Cobra is going to be a street car, then you need an engine that produces good torque from 1,500 to 5,000 because that’s the operating RPM on the street.


A small- or big-block engine with dual quad carbs, single-plane intake, large port heads, and a high-lift, long-duration cam that produces its best power from 6,000 to 7,500 rpm is not suited for the street. But an engine such as this is ideal for road racing because it spends most of its time at high RPM. Drag engines also spend much time at the top end of the powerband. A race-type engine is such a pain to drive on the street because it doesn’t idle evenly at stop lights and doesn’t carburate well at lower RPM. Therefore, you often must rev the engine and slip the clutch from intersection launches. And it doesn’t pull very hard out of low-speed corners.


Ford Small-Blocks

The Ford Windsor small-blocks in 260, 289, 302, and 351 displacements as well as Cleveland’s in 351 and 400 displacements have been popular engines for Cobra replicas since the inception of the market. All the small-block Fords have a deck height of 4.185 inches and easily fit into the Cobra. You can build these engines with any combination of stock components, but most owners build a small-block using premium components of forged crank, rods, and pistons, and opt for a high-performance set of aluminium heads.

Many Cobra owners opt to build a stroker combination on a stock cast-iron or aluminium block. Many of the stroker assemblies are less expensive than factory-rebuilt parts, so for many owners this is a no-brainer and they go with this option. The 302 with 3-inch stroke and the raised-deck 351 Windsor’s and 351 Cleveland’s with 3.5-inch stroke are excellent platforms for stroker combinations, as is the 400M, which is a taller-deck Cleveland.

For the 302, stroker combinations in 331, 347, and 355 displacements are popular. And for the 351 and 400 blocks, displacements of 383, 393, and 408 ci are popular stroker combinations. Scat, Eagle, Coast High Performance, and many other businesses offer high-quality stroker combinations to fit Windsor and Cleveland blocks, so you can find a setup that works for your car and application.


Ford Big-Blocks

The Ford FE 427-ci side-oiler engine was standard equipment in the original Shelby Cobra, and many of the Cobra faithful opt to put an FE engine in their Cobra replicas. The FE (Ford Edsel) engines were built from 1958–1976 to power a wide range of Ford passenger cars, so there are a lot of blocks and engines available. Ford offered the FE in 332, 352, 360, 390, 406, 410, 427, and 428 displacements. Several stroker combinations are available for the FE engine, including 434, 445, and 505 displacements. Survival Motorsports is a leading FE engine builder and offers a full line of engine components and services for FE engines.

The Ford 385 Series or Lima big-block engines are popular with owners who must have extreme displacement. The 370, 429 and 460 engines were offered from 1968 until 1967, and these replaced the MEL (Mercury, Edsel, and Lincoln) engines. The Lima engines were extensively installed in large passenger cars, trucks, and of course Mustangs and high-performance Torinos. The standard 429 engine featured a two-bolt main bearing cap, cast-iron cam, cast-aluminum pistons, forged-steel connection rods, hydraulic cam, and non-adjustable rocker arms.


The Cobra Jet and Super Cobra Jet became Ford’s most notable big-blocks. The 370-hp Cobra Jet and 375-hp Super Cobra Jet featured four-bolt main bearing caps, 2.25-inch intake, 1.72-inch exhaust heads, and a lot of other high-performance equipment. The Cobra Jet used threaded in rocker arms. The Super Cobra Jet was equipped with forged aluminium pistons, mechanical cam, and 780- cfm Holley carb. These engines were installed in the Mustang Mach 1, Torino Cobra, and many other cars. Many of the standard performance engines have two-bolt main bearing cap block, while the Cobra Jets feature four-bolt main bearing caps.



Crate Engines

Many used Ford small-block and big-block engines have been rebuilt and over-bored beyond their limits and, therefore, are unuseable. Many owners do not want to pluck a used engine from a Mustang or other performance Ford car and perform a high-performance build up, they want a crate engine. There are many suppliers, such as Ford Racing Performance Parts, Mustangs Plus, Edelbrock, World Products, Roush Engines, Coast High Performance.

Crate engine prices run the entire gamut, and it depends upon equipment package in the engine. Mild-performance, small-block crate engines are sold for $3 000 and more while high-performance smallblocks, with forged rotating assemblies and high-performance heads and valvetrain, start at $5 000.


As with any engine, you need to select the right one for your car. The engine should have the correct equipment package for the horsepower and torque output. A 300-hp small-block crate engine can carry a stock rotating assembly, but if you’re buying a small-block to make 600 hp, it needs to carry forged rotating assembly and other high-performance running gear.

Big-block crate engines are also available from many of the same suppliers, but for a big-block you are entering a new tier of performance and a much higher price. Big-blocks often start at $7,000.


Therefore, when you’re doing research, you need to determine the best engine package for your car and application. Make sure your engine and transmission combination are compatible with your particular kit and whichever cross-member modifications and motor mounts are required to mount it.


Les Hayden has been building Cobras since the early eighties, he has built Cobras with most of these different configurations and will be glad to advise you on the right choice for your Cobra.

Hayden Cobra offers full factory assembled Cobras with your choice of engine and transmission installed. Contact us today to learn how you too can become a proud owner!



Thanks to www.diyford.com for contributing to the post.

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Montague Gardens, Cape Town, 7441, South Africa

+27 83 991 6154

+27 21 551 1947

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