Important upgrades in the 289 occurred for the 1965 model year beginning in August 1964. The most obvious was a block casting change from a five-bolt bellhousing pattern to a six-bolt to improve noise, vibration, and harshness. Aside from this important change, the 289 remained essentially the same, with the base 289-2V engine retaining 52.6- to 55.6-cc combustion chambers and dished pistons to keep compression at 9.0:1. Valve sizes remained the same.
The 289-4V engine went from sharing dished pistons and the same compression ratio to 10.0:1 and flat-top pistons for 1965. All pistons, flat-top and dished alike, had valve reliefs. The 289 High Performance V-8 remained virtually unchanged aside from the six-bolt bellhousing block and a higher compression ratio.
As of May 2, 1966, Ford went to a rail-style rocker arm and pent-roof (flat-top) valve covers on 289-2V/4V engines, which continued through the 1967 model year. This 289-4V engine has California emissions closed crank-case ventilation.
The 289 didn’t change for 1966 aside from engine color. California emission standards became tougher for 1966, calling for not only closed crankcase ventilation, but also Ford’s Thermactor air-injection pump system to help completely burn hydrocarbon emissions.
Effective May 2, 1966, 289-2V and 4V engines received important cylinder head and valvetrain changes: rail-style rocker arms, longer valvestems, revised cylinder head castings, and pent-roof (flat-top) valvecovers. The pent-roof-style valvecovers were in production through the 1967 model year.
One subtle change during the 1966 model year was the short-term use of a finned timing cover through early 1967. Although the 289 High Performance V-8 never employed rail-style rocker arms, it did use pent-roof valvecovers with a chrome finish and High Performance open-element air cleaner for 1967.
Production of the 289 ended in 1968.
For 1968, Ford went to a pent-roof “Power By Ford” valvecover as well as a redesigned air cleaner assembly for 289/302 engines, all with closed crankcase ventilation for 50-state use. The 289/302 also were equipped with Improved Combustion (IMCO) with a coolant temperature–activated spark timing vacuum control valve. This is the “J” code 302-4V V-8 with Autolite 4300 carburetion in a 1968 Mustang.
Shown is a 1970 302-2V V-8 with the same basic small-block Ford air cleaner introduced in 1968. Beneath this air cleaner is a more emissions-friendly 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.
