Stroking A 400 Pontiac: Is It Possible?

The Pontiac 400 is a popular V8 engine that was first introduced in 1967. Over the years, there have been various iterations of the 400, with different bore and stroke lengths. When it comes to stroking a 400, there are a few things to consider. Firstly, stroking the engine will result in increased torque and power output. This can be advantageous for those who want more low-end power and improved acceleration. However, it is important to note that stroking the engine may also increase fuel consumption and put more strain on the drivetrain, potentially leading to increased wear and tear on certain components.

Another consideration is the cooling system. A larger stroke can generate more heat, which may require upgrades to the cooling system to prevent overheating. Additionally, the increased stroke length can also lead to higher piston speeds and increased side loading on the cylinder walls, which can affect engine durability.

When deciding whether to stroke a 400, it is essential to weigh the benefits against the potential drawbacks. For a street-driven car, a 400 with a mild stroke can provide a good balance of power and drivability. However, for those seeking maximum performance, a longer stroke can be combined with other modifications to extract more power from the engine. Ultimately, the decision to stroke a 400 depends on the intended use of the vehicle and the driver's preferences for power and torque.

The Pontiac 400 was introduced in 1967 and remained in production until 1978

The 400 was introduced as the high-performance engine option for the Firebird and GTO. It was rated at 325-445 lb-ft of torque and 180-370 bhp. The 400 was also fitted to less powerful and civilian-aimed cars like the Pontiac Safari.

In 1967, the 400 switched from closed to open chamber heads, improving breathability and airflow through the engine. The valve angle was also changed from 17 to 14 degrees. The 400 was given a high-performance Rochester Quadrajet carburettor, and long-tube exhaust manifolds were added.

The 400 was also available with the "Ram Air" package, which included functional hood scoops, higher flow heads with stronger valve springs, and a hotter camshaft. The "Ram Air II V8" featured round exhaust ports, which increased exhaust flow and made header installation easier. The "Ram Air III" and "Ram Air IV" were released in 1969 and 1970, respectively. The Ram Air IV went back to circular port heads and featured redesigned intake ports, an aluminium intake, and a cam with significantly increased lift.

By 1970, the 400 was approaching a cliff due to the introduction of the new big block 455 HO V8, and the tightening of emissions standards. The 400 remained in production until 1978, with power output dropping from 370 horsepower at its peak from 1967-1970 to a measly 180 horsepower in 1978.

The 400 was Pontiac's most popular V8 engine

The Pontiac 400 V8 engine was introduced in 1967 as a high-performance engine option for the Firebird and GTO. It was one of the last Pontiac big-block V8s ever produced by the company and shared a nearly identical design with the earlier 389 V8 that it was based on. The only real change was to the bore of the engine, accounting for the additional displacement.

The 400 was one of the most popular V8s produced by Pontiac and was used in some of the most iconic Pontiac models, including the Firebird and GTO. Over the course of its production run, Pontiac offered the engine in different configurations, primarily differing by carburettor type and intake system. Early 2-barrel variants of the 400 V8 were fitted to less powerful and civilian-aimed cars like the Pontiac Safari, while 4-barrel versions ranged in power from 330 to 370 horsepower.

The 400 was also the basis for a series of "Ram Air" performance engines, with the first of these, the Ram Air II, released in 1968. This engine featured a revised cylinder head with round exhaust ports, a more aggressive camshaft, and a beefed-up valvetrain. Later Ram Air III and Ram Air IV engines built on these improvements, with the Ram Air IV featuring redesigned intake ports, an aluminium intake, and a cam with significantly increased lift.

The 400 remained in production until 1978, by which time much had changed in the automotive world. The oil crisis of 1973 and the introduction of stricter emissions standards had made large-displacement, high-performance V8s increasingly unfeasible. The power output of the 400 V8 dropped from a peak of 370 horsepower in 1967-1970 to just 180 horsepower in 1978.

The 400 was available with two-barrel, four-barrel, and Tri-Power carburetion

The Pontiac V8 engine was manufactured between 1955 and 1981 and was available in a variety of configurations, including the 400, which was introduced in 1967. The 400 was a popular performance option for many Pontiac models, and when combined with other high-airflow components, it delivered an excellent balance of low-end torque and higher-RPM power.

The four-barrel carburetor, on the other hand, features four venturis, allowing for even better fuel atomisation and more precise fuel delivery. This type of carburetor is often associated with high-performance engines and is commonly found in racing applications.

The Tri-Power carburetor, also known as the triple carburetor, was a unique offering from Pontiac. It consisted of three two-barrel carburetors with a sequential linkage, providing an even greater level of performance and customisation. This setup was first introduced by Pontiac in 1957 and became a popular option for those seeking maximum power and responsiveness from their vehicles.

The availability of these different carburetion options allowed Pontiac 400 owners to customise their vehicles to their desired performance levels, whether it was for everyday driving, racing, or somewhere in between. Each option provided a distinct driving experience, with the two-barrel offering a balance of performance and efficiency, the four-barrel delivering high-end power, and the Tri-Power providing the ultimate in responsiveness and acceleration.

The 400 was replaced by the 455 in 1970

The 455's debut in 1970 was a result of General Motors lifting its restriction on engines larger than 400 cubic inches in mid-size cars. This opened the door for GM divisions Oldsmobile, Buick, and Pontiac to introduce their own versions of the 455. However, the development of the 455 in Pontiac was impacted by a corporate shake-up, with John DeLorean's promotion to General Manager of Chevrolet leading to James McDonald taking over Pontiac. McDonald's focus on sales and cost-cutting meant that projects like the Ram Air V were discontinued, leaving the 455 with less development time.

The 455 in the GTO was rated at 360 horsepower, which was less than the previous 400 Ram Air engines. The Firebird Trans Am and Formula models also offered the 455 HO, which included round-port cylinder heads and an improved camshaft, resulting in a rating of 335 horsepower. This engine was available until 1972, with few changes.

In 1973, Pontiac introduced the Super Duty 455, which featured a strengthened cylinder block, forged connecting rods, and unique high-flow cylinder heads. This engine was only available in the Firebird Formula and Trans Am models, and its production was limited due to emissions regulations. The Super Duty 455 was discontinued after 1974, and the standard 455 continued until 1976, when it was phased out due to tightening emissions standards.

The 400 was phased out in 1979

The 400 remained in production through the 1978 model year, with 1979 cars receiving engines produced the previous year. The 400 was discontinued as the 1978 model year came to a close, with the Division stockpiling and earmarking several thousand PN XX481988 blocks from the 1978 model year for use in 1979. That inventory was exhausted by May 1979, and the 400-powered Trans Am went away forever.

The 400 was one of the last Pontiac big block V8s ever produced by the company. By the time 1970 rolled around, the 400 CID V8 was approaching a cliff that no one could've predicted. One of the main things that initially pushed the 400 V8 into the background was the introduction of the Pontiac 455 HO V8. With the implementation of new SAE net horsepower rating requirements, the power of post-1972 engines appears pitiful. The same can be said for the engines of other manufacturers at the time too. With lower compression, increased emission-regulating equipment, and overall dulling of the engine, the Pontiac 400 V8 went from 370 horsepower at its peak from 1967-1970 to a measly 180 horsepower in 1978.

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