How to decode the evolution of Ford's 427, 428, and 429 big block muscle


Ford 427, 428, 429. What do these similar numbers tell us about very different engines?

To the uninitiated, Ford's big inch performance motors all seem basically the same, with slightly different displacements. Nothing could be further from the truth. That last digit can make a really big difference in both performance and value of Blue Oval muscle.

Rather than try to spell out every technical aspect of these engines, let's look at them as they relate to cars that interest us-namely, Shelby and Mustang cars. The 427 and 428 engines are both from the "FE" family, in production from 1958-76, with engines that ranged from 332 cubic inches to 428. The first performance-era FE was the HiPo 390, followed by the 406, which was developed for racing and based on this 390, but with a thicker walled casting block, cross-bolted main bearing caps for high-rpm abuse, and assorted other tricks. After two years, the 406 was further developed into the 427, which was introduced in 1963 with its sights set squarely on winning races.

One term tossed around with 427 engines is "side oiler." The first 427s were "top oilers," which sent oil from the pump to the valve train first and the crankshaft second. These early engines had lubrication issues caused by oil sloshing away from the oil pump pickup under hard acceleration and cornering, earning them a reputation for eating crankshafts. The real fix was fitting a crank windage tray and baffled oil pans, but to make sure the oil system was sufficient for competition use, Ford modified it to pressurize the crankshaft main bearings first, then the valvetrain. The term "side oiler" comes from the oil galleys clearly visible where they are cast into the side of the block to feed the main bearings oil. The side oiler was put into production in 1965, perfect timing for the 427 Cobra.

428 much cheaper to build

The 428 was a more production-based affair and much cheaper to build. It was brought in to meet the demand for a higher-production, more cost-effective performance motor.

The FE motors were superceded by the "385" family of engines in the late 1960s. The 429 is from the 385 family and was an entirely new design. In 1968, this was the latest and greatest big Ford motor, with numerous upgrades from the then decade-old FE HiPo design on which the 427 was based. The Boss 429 engine introduced in 1969 was based on this 385 block, as well as the numerous non-Boss hemi head versions used in other muscle Ford products. The later 460-ci engines are also based on this 385 architecture.

So let's get back to how this relates to certain cars. In the Cobra world, not all of the "427" Cobras were built alike. The entire 427 Cobra production run went from chassis number 3001 to 3360. Chassis numbers 3001-3200 had the 427 engine. By late 1965, Ford was having difficulties meeting demand for the 427. Shelby was 80 cars into his 427 Cobra production and was given the option to either wait for 427s or consider the new 428 engine. The 428 was a hydraulic-lifter, lower-rpm motor that was better suited to the street Cobra buyer. An added bonus was that they cost Shelby $320 each, versus the $730 for a 427.

Shelby decided that starting at chassis #3201, the 428 would be the standard Cobra motor. Eventually, engineer Fred Goodell came on board and decided if the car said "427" it should have a real 427 in it, and around chassis #3301, 427 Cobras were again just that. A few 3300 cars had a 428, namely 3301, 3305, and 3306, but the balance all had a 427 under the bonnet. For years, the Cobra purists have shunned the 3200 cars due to the 428 engine, and while most would never know the difference from driving them, in the market a "428" car is worth about 10%-15% less than a 427 car.

No Mustang or Shelby 427s

No Mustang, Shelby, or otherwise, left the factory with a 427 as standard equipment. A few cars were fitted with a 427 for testing purposes, such as the 1967 GT500 "Super Snake," but if somebody tries to sell you a factory "427" Mustang, run, don't walk. The 428 was the engine of choice, and has multiple variations depending on fitment. In 1967, the 428 Police Interceptor engine was standard in the GT500, with 2x4 induction, stronger internals, and an aluminum intake manifold. In 1968, the 428 Cobra Jet engine was available mid-year in both the Mustang and GT500 KR. The CJ motor had better heads, a stronger block, and other improvements.

By 1969, the Super Cobra Jet was available, and featured forged pistons, 427 "Le Mans" connecting rods, various heavy duty components, and standard engine oil cooler. If you ordered a 3.91 or 4.30 rear axle ratio you would automatically get an SCJ motor. It was Ford's attempt to keep engine internals where they should be for as long as possible. Various other performance Fords and Mercurys could be ordered with the 428 CJ or SCJ engines. Obviously, the top dog is the tough SCJ unit, whether it is in a Shelby or a Mustang.

Nineteen sixty-nine saw the introduction of the new 385 series with the Boss 429 engine. This new motor was built to be a NASCAR and NHRA star, and Ford pulled out all the stops. It had a thin-wall block casting, huge main bearings, special oiling system, four-bolt main bearing caps, and aluminum semi-hemispherical cylinder heads with huge ports and valves. The 429 was an incredible piece. To go racing, Ford had to make this motor available to the public. They decided to have Kar Kraft Industries cut, chop, and hammer this behemoth into the 1969 Mustang-and they sold enough to homologate it. Though a great performer on the track, when it was detuned for street use in the Boss 429 Mustang, in stock form it was a disappointment. Only 1,358 Boss 429 Mustangs were produced in 1969 and 1970. With all of its specific parts and modifications, Boss 429 components are not interchangeable with other 385 series engines.

By late 1970, the standard 428 CJ/SCJ motor was phased out and replaced by the new 429 Cobra Jet. In 1971, the 429 Super Cobra Jet was available, and it was an awesome performer. The 429 SCJ was a solid-lifter engine with four-bolt mains, a cast-iron crank, forged pistons, external oil cooler, and all the right stuff. A 1971 Mustang with the 429 SCJ was the fastest Mustang built to that point. Although usually overlooked, the 429 SCJ deserves a lot more respect than it receives.

By 1973, the 429 was gone, replaced by the 460, which never had a factory hot rod package like the earlier 390/406/427/428/429 motors did.

While this is nowhere near a definitive work on Ford performance engines, it will help clear the air. And the next time somebody starts telling you about their ultra-rare 1969 Mustang with the factory 429 side-oiler engine, you can tell them you have a bridge to trade them for their collectible car.

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