Stroking An Olds 455: How Far Is Too Far?

how far can I stroke an olds 455

The Oldsmobile 455 engine was produced from 1968 to 1976 and was installed in almost every car the company built during that period. The engine's displacement ranges from 400 to 455 cubic inches, with horsepower ratings from 210 to 400. The 455 is known for its impressive torque, with 500 lb-ft being a common figure.

The 455's bore and stroke are 4.126 inches and 4.25 inches, respectively, but some engines have been modified with a 4.185-inch bore. The engine block can be overbored to accommodate larger displacements, with some builders opting for a 4.5-inch stroke crankshaft to create a 488 cubic inch engine.

When modifying the 455 for more power, common upgrades include forged pistons, aftermarket cylinder heads, and higher compression ratios. The engine's bottom end is generally reliable, but attention must be paid to oil control and bearing clearances to handle the increased power output.

The Oldsmobile 455 is a popular choice for enthusiasts looking to build a high-performance engine, and with its robust design and ample torque, it serves as an excellent foundation for a variety of applications, from street cruisers to drag strip contenders.

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How to identify an Olds 455 engine

The Oldsmobile 455 engine, also known as the Rocket 455, was produced from 1968 to 1976. It was used in a variety of vehicles, including the iconic Olds 442 muscle car, as well as the Delta 88, Toronado, Cutlass/442, and several luxury sedans.

  • Check the casting letter: Look for a 1" high casting letter on the lower-left corner of the block and/or head. This can give you a quick estimate of the engine's year.
  • Carburettor numbers: For engines manufactured before 1973, all models used the same carburettor numbers, except for high-performance and Toronado engines. From 1973 onwards, carburettor numbers were calibrated for specific models due to emissions regulations.
  • Distributor number: The distributor number may also be specific to the model the engine was installed in, especially for later engines.
  • Exhaust manifolds: If the passenger-side manifold has two openings, it likely came from an 88 or 98 model.
  • VIN derivative stamp: The VIN derivative stamp on the block can help identify the year of the engine. For example, "39M" would indicate a 1969 engine, while "30M" would be a 1970 model.
  • Engine colour: The Toronado engines were painted a light metallic blue, while the 1970 442 motors were a deeper blue.
  • Valve covers: The Toronado valve covers had no notches, while the 442 valve covers had notched valve covers for clearance at the back.
  • Oil filter adapter: The Toronado oil filter adapter sticks out further from the engine and angles forward to clear the Toronado starter. The Cutlass oil filter adapter would be closer to the block.
  • Oil pan: The Toronado oil pan is deeper and has a raised notch in the middle for the front halfshaft, while the 442 oil pan slopes evenly from the front to the sump.

These details can help identify the year, model, and specific variations of the Olds 455 engine.

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The Oldsmobile 455's horsepower and torque

The Oldsmobile 455, also known as the Rocket 455, was a V8 engine produced from 1968 to 1976. It was the largest of a trio of engines (400, 425, and 455) that shared a similar architecture. The 455 offered between 210 and 400 hp, but it was the 500 lb-ft of torque that really made it a star.

The 455 had a 4.126-inch bore combined with a 4.25-inch stroke. Factory horsepower ratings ranged from 310 all the way up to 400, with 500 lb-ft the most common torque figure. The engine was used in a wide range of vehicles, including the popular 442 muscle car, the larger, family-oriented Delta 88, the 98 luxury sedans, and even in the front-wheel-drive Toronado.

The 455 was a very forgiving and long-lasting engine. To increase horsepower, one could go with higher compression, which would prevent pump gas usage (the highest stock compression ratio was 10.5:1). This could be achieved by using flat-top pistons, milling heads, and decking the block, resulting in a compression ratio in the 14-range. However, this would come at the cost of increased wear and tear.

The Oldsmobile 455 was a versatile engine that delivered impressive horsepower and torque figures. It was used in various vehicles, from muscle cars to luxury sedans, and its longevity and performance made it a popular choice for hot rodders and classic car restorers.

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The Oldsmobile 455's engine modifications

The Oldsmobile 455 engine was produced from 1968 to 1976 and was installed in almost every car Oldsmobile built during that period. The engine's displacement resulted from a 4.126-inch bore combined with a 4.25-inch stroke.

Modifications

Stroke

You can increase the engine's displacement by stroking it. A 4.5-inch stroke crankshaft can be used to achieve a displacement of 488 cubic inches. This requires some clearancing at the bottom of the block, but it does not weaken the structure.

Pistons

It is recommended to use forged pistons, which are not much more expensive than cast pistons for the Oldsmobile engine. Forged pistons offer superior strength and heat dissipation.

Crankshaft

When increasing the stroke, it is important to check the crankshaft for straightness and ensure the journals are correct. The crankshaft journals may need to be turned down for jet boat applications.

Connecting Rods

Connecting rods with BBC rod journals can be used with a 4.5-inch stroke crankshaft. A 7.1-inch BBC rod is ideal for this combination.

Heads

Edelbrock 6102 aluminum heads are a good choice for the Oldsmobile 455 engine. These heads feature a redesigned 77cc combustion chamber, larger intake valves, and improved bowl blending for better flow.

Camshaft

A hydraulic roller camshaft is a suitable choice for the Oldsmobile 455 engine. A conservative camshaft with a duration of around 224 can still provide impressive torque output.

Carburetor

A Quick Fuel Technology (QFT) Street-Q 850 CFM carburetor is a good choice for the Oldsmobile 455 engine.

Intake Manifold

The Edelbrock Performer intake manifold is a suitable choice for the Oldsmobile 455 engine. It has an intake height of 4.95 inches and improves torque and throttle response from idle to 5,500 rpm.

Ignition

An MSD ignition system with a billet distributor, 8.5mm wires, and a Blaster coil can be used to spark the engine.

Hooker headers with a size of 2.125 inches can be used with the Oldsmobile 455 engine.

The Oldsmobile 455 engine has a lot of potential for modification. By stroking the engine, upgrading the pistons, crankshaft, connecting rods, heads, camshaft, carburetor, intake manifold, ignition system, and headers, you can significantly enhance its performance.

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The Oldsmobile 455's crankshaft and connecting rods

The crankshaft is the part of an engine that changes the up-and-down motion of the pistons into rotational motion. The connecting rods are the parts that connect the pistons to the crankshaft.

The Oldsmobile 455 big-block engine was produced from 1968 to 1976 and was used in a variety of Oldsmobile models, including the iconic 442 muscle car, as well as family-friendly and luxury vehicles. The 455 offered between 310 and 400 horsepower, but it was the 500 lb-ft of torque that really made it a star.

The crankshaft in the Oldsmobile 455 engine has a 4.25-inch stroke. There are a few different types of crankshafts that can be used in the 455 engine, depending on the year and model of the vehicle. The early big-block forged steel crankshafts had a 3.975-inch stroke and were used in the 442's early 400 engines and all 425's. These crankshafts can also be used to build a 455 small block using a 350 Diesel block and about $3000 worth of Mondello parts.

For 455 usage, a cast crankshaft is almost always used. These cast 455 crankshafts come in two varieties, both with the same casting number (397363). The superior type is constructed of "nodular iron" and has a prominent "N" cast onto the side of the front counterweight. These crankshafts were found in the majority of 455s produced between 1968 and 1972, especially in high-performance models like the Toronado and 442/Toro/W-30.

The other type of cast crankshaft used in the 455 engine is made of plain iron and lacks the "N" on the front weight. This type of crankshaft is considered weaker than the nodular iron version.

When it comes to connecting rods, there are a few options available for the Oldsmobile 455 engine. One option is to use stock connecting rods, which are adequate for most applications. However, if you are building a high-performance engine or seeking increased durability, aftermarket connecting rods from companies like Eagle Specialty Products may be a better choice. These aftermarket connecting rods are typically made from forged steel and offer greater strength and durability than stock connecting rods.

In summary, the crankshaft and connecting rods are critical components of the Oldsmobile 455 engine, and the choice of these components can significantly impact the performance and durability of the engine. While stock parts may be sufficient for some applications, high-performance engines or those seeking increased reliability may benefit from aftermarket crankshafts and connecting rods designed specifically for the 455 engine.

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The Oldsmobile 455's engine block machining

The Oldsmobile 455 engine was produced from 1968 to 1976 and was installed in almost every car Oldsmobile built during that period. The engine's versatility is reflected in its use in the popular 442 muscle car, the family-oriented Delta 88, the 98 luxury sedans, and even the front-wheel-drive Toronado.

The Oldsmobile 455 engine block machining process involves several steps to ensure optimal performance and longevity. Here are some key aspects of the machining process:

  • Boring and Honing: This process involves increasing the diameter of the engine's cylinders to accommodate larger pistons, which can increase displacement and power output. It is important to use a torque plate during this process to ensure that the cylinders remain as round as possible when the cylinder heads are installed.
  • Balancing: Balancing the rotating assembly, including the crankshaft, pistons, and connecting rods, is crucial to ensure smooth operation and reduce vibrations.
  • Decking: Decking, or resurfacing, the engine block helps ensure that the block is flat and parallel to the crankshaft. This process can also be used to adjust the compression ratio by changing the distance between the piston and the cylinder head.
  • Clearancing: Minor grinding or clearancing may be required for rod clearance. It is important to remove only the necessary material to maintain the structural integrity of the block.
  • Oil System Modifications: The Oldsmobile 455 is known for its impressive torque output. However, its small oil return passages can limit its ability to withstand sustained high RPM use. Upgrades such as a larger oil pan and an oiling restriction system can help address this issue.
  • Rear Main Seal: Replacing the factory rope rear main seal with a neoprene lip seal, such as the one from the Ford 460 big block, can improve reliability and prevent oil leaks.
  • Camshaft Bearing Oil Restrictors: Installing cam bearing restrictors can help direct more oil to the main bearings, ensuring adequate lubrication.
  • Cylinder Head Machining: While the stock cylinder heads may be adequate for a conservative build, for more power, consider upgrading to aftermarket aluminium cylinder heads, such as the Edelbrock Performer RPM heads. These heads offer improved flow characteristics and can be further enhanced with modifications like a 30-degree back-cut on the intake valves.

The Oldsmobile 455 engine is a popular choice for enthusiasts due to its availability, torque output, and responsiveness to camshaft upgrades. With careful component selection and machining, a reliable and powerful engine can be built within most budgets.

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Frequently asked questions

The Oldsmobile 455 big-block was produced from 1968 to 1976 and offered between 310 and 400 hp, with 500 lb-ft of torque. The pros of the Olds 455 include its high torque output, which makes it suitable for hot rods and muscle cars. The engine is also relatively easy to identify and has a long-lasting design. However, one con of the Olds 455 is that it may require modifications or upgrades to achieve higher horsepower, and there can be challenges in finding compatible performance parts due to its unique design.

The maximum stroke achievable with an Olds 455 depends on various factors, including the specific engine configuration and modifications. Some builders have achieved strokes of up to 4.5 inches by using aftermarket crankshafts and connecting rods. It is important to consult with experts or specialized forums for guidance on the feasibility and potential trade-offs of such modifications.

When stroking an Olds 455, common issues and challenges include finding compatible performance parts, such as crankshafts and connecting rods, that fit the engine's unique design. Additionally, achieving higher horsepower may require significant modifications or upgrades, and there can be concerns about the integrity and durability of the block when making such modifications. It is crucial to consult with experienced builders or specialists before attempting any engine modifications.

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