Ford Small-Block Engine Parts Interchange. George Reid
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Autolite 2100 carburetor with evaporative emissions and a more aggressive choke pull-off.
Ford’s 289-ci V-8 witnessed such great success across the board as both a fiercely dependable street engine and a world-beating performer on the racing circuit that you wouldn’t think Ford would disturb this success, but it did with a small increase in stroke. Pressure from increasing displacements at Chevrolet, Pontiac, and Chrysler pushed Ford toward adding more stroke to the tried-and-proven 289 to get 302 ci.
The additional stroke was challenging to measure at .013 inch, bringing the small-block Ford’s stroke to 3.000 inches. Ford had to revise the block, extending cylinder skirts .015 inch for improved piston stability at bottom dead center. Some 1967–1968 289 engines received 302 blocks as early as February 1967. This was toward the end of the 1967 model year before the 302 entered production.
Although the 302 has a longer 3.000-inch stroke, it has a shorter C8OE connecting rod (5.090 inches center-to-center); it is not interchangeable with the C3AE 221/260/289 rod (5.155 inches center-to-center). The 302’s shorter rod, when combined with the longer 3.000-inch stroke 2M crankshaft, gives this engine its increased displacement. Aside from those small differences, the 302 is virtually identical to the 289, including valve size and combustion chamber design.
One exception is the 1968-only 302-4V “J” head with smaller 53-cc chambers and higher compression. It is higher compression (premium fuel) because compression is the easiest means to increased power. What makes 1968 engines visually different than 1967 are the words “Power By Ford” stamped into their pent-roof valvecovers. These words appeared on all Ford valvecovers that year and continued until 1975 when they were replaced by the Ford corporate oval.
The 302 has evolved considerably since its introduction in 1968. Beginning in 1978, Ford changed the engine’s designation from a “302-ci” to “5.0-liter” (5.0L) V-8 as the United States became pressured to employ the metric system. In 1978, Ford also began fitting the 302 and other engines with a stamped aluminum air cleaner to reduce vehicle weight.
When Ford reintroduced the Mustang GT in 1982, it fitted the timeless pony with a High Output version of the 5.0L V-8. Although quite tame by today’s standards, the 5.0L High Output had a high-performance 351W Marine camshaft (and 351W firing order) coupled with a Motor-craft 2150 2-barrel carburetor and dual-snorkel aluminum air cleaner. The bottom end also changed to accommodate the increase in performance. Instead of the 289/302’s 28-ounce offset dynamic balance, the 5.0L High Output had a 50-ounce offset balance, which is very important to remember when you’re building these engines. Get it mixed up and you have unwanted, severe engine-punishing vibration.
In 1983, Ford began fitting the 5.0L High Output V-8 with the Holley 4180 4-barrel carburetor, which was a Holley-designed, Ford-engineered performance/emissions/tamper-proof carburetor. This carburetor, aside from minor engineering changes, remained essentially the same through 1985 along with the proven Motorcraft Duraspark II ignition system. In 1985, the 5.0L High Output V-8 received an all-new roller-tappet block designed to accommodate roller cam technology to improve both power and fuel efficiency.
In 1986, the small-block Ford received the most dramatic change in its history: port fuel injection. Known as Sequential Electronic Fuel Injection (SEFI), this new system of fuel delivery and spark control (EEC-IV) was the single biggest quantum leap in technology for the Fairlane V-8 because it wasn’t just port fuel injection, but complete electronic engine management. The 1986 5.0L High Output was fitted with “high-swirl” chamber cylinder heads and experienced a loss in horsepower and an increase in torque.
Although the 5.0L SEFI High Output engine was intimidating for enthusiasts in the beginning, people ultimately embraced this power plant and went racing with a new attitude known as “PRO 5.0,” building powerful Mustang rocket ships. It was so successful that it spawned a new organization known as the National Mustang Racers Association (NMRA), which has become a huge Mustang subculture. This was an exciting new chapter for the industry that, at press time, shows no signs of fading away. Despite a drastic blow to the economy, enthusiasts are still racing the 5.0L small-block Ford in record numbers. The 5.0L High Output V-8 has grown to become one of the most respected high-performance engines of our time.
Beginning in 1971, Ford’s 302-ci small-block received this smaller redesigned air cleaner assembly, which was in production through 1976.
Beginning in the 1977 model year, Ford fitted all of its small-blocks with aluminum air cleaners for weight-reduction purposes. This is a 1978 5.0L-2V small-block in a Mustang II with the Motorcraft 2150 emissions 2-barrel carburetor and Duraspark ignition.
Ford introduced the 5.0L High Output Sequential Electronic Fuel Injection (SEFI) in 1986 with 62- to 65-cc “High-Swirl” chambers and 200 hp on tap. It remains unknown 30 years later why the “5.0L Liter HO” graphics were sideways on these.
For 1987–1993, the 5.0L High Output SEFI V-8 delivered 225 hp and 300 ft-lbs of torque thanks to induction and cam improvements coupled with the fast-burn–chamber 1985 truck head.
Here’s the 240-horse 1994–1995 SVT Mustang Cobra 5.0L V-8 sporting GT-40 cylinder heads and induction. The GT-40 cylinder head was produced in cast iron and aluminum, available from Ford Motorsport SVO and Ford Racing.
This is the 1994–1995 5.0L High Output V-8 with the low-profile induction system for hood clearance, which hurt horsepower, yet improved torque.
In 1987–1993, Ford went back to the tried-and-proven fast-burn–chamber cylinder head, which was actually a truck casting that worked very well with SEFI, netting an increase in horsepower and torque.
Like the rest of Detroit in the late 1970s, Ford looked for ways to squeeze more mileage from a gallon of gasoline. The 255-ci (4.2L) small-block, which was produced at Ford’s Windsor, Ontario, foundry and engine plant, was a short-lived answer to a long-term challenge: fuel economy. Produced from 1980 to 1982 only, the 255 never cultivated a performance image because that’s not what it was designed to do. It was the only V-8 engine available in the Mustang in 1980–1981.
The baby Ford small-block has the same 3.000-inch stroke as the 302 with a smaller 3.680-inch bore. It has 255-specific cylinder heads with smaller combustion chambers and valves with round ports and absolutely no performance potential whatsoever. The 255 also had its own unique, lightweight hollow-core nodular iron crankshaft, yet with the 302’s 5.090-inch rods.
The 255 was a very short-lived chapter in small-block Ford history and one of the most forgotten engines of our time. It was fitted with either the 49-state Motorcraft 2150 carburetors or the California-only Motorcraft VV carburetor.