What is the difference between a 153 and 168 tooth flywheel?

The main difference between a 153 and 168 tooth flywheel lies in the number of teeth they have. A 153 tooth flywheel has 153 teeth, while a 168 tooth flywheel has 168 teeth. This seemingly small difference can have significant implications for the performance and compatibility of an engine.

Understanding Flywheels

A flywheel is a heavy, rotating disc that is attached to the crankshaft of an engine. Its primary function is to store and release energy, helping to smooth out the uneven power delivery from the engine's cylinders. The number of teeth on a flywheel corresponds to the number of times the engine's crankshaft rotates per revolution of the flywheel.

153 Tooth vs. 168 Tooth Flywheels

The key differences between a 153 and 168 tooth flywheel are:

• Tooth Count: As mentioned, a 153 tooth flywheel has 153 teeth, while a 168 tooth flywheel has 168 teeth.


• Engine Compatibility: The number of teeth on a flywheel must match the engine's specifications. Using the wrong flywheel can cause issues with the engine's timing and performance.


• Gear Ratio: The gear ratio, which determines the relationship between the engine's crankshaft and the transmission, is affected by the number of teeth on the flywheel. A 168 tooth flywheel will have a different gear ratio than a 153 tooth flywheel.


• Torque Capacity: The increased number of teeth on a 168 tooth flywheel can provide slightly more torque capacity compared to a 153 tooth flywheel.

It's important to note that the specific requirements for a flywheel can vary depending on the engine, transmission, and other components in the vehicle. Always consult the manufacturer's recommendations when selecting a replacement flywheel.

Conclusion

In summary, the primary difference between a 153 and 168 tooth flywheel is the number of teeth they have. This seemingly small difference can have significant implications for an engine's performance, compatibility, and gear ratio. When replacing a flywheel, it's crucial to ensure that the new one matches the engine's specifications to avoid any issues.

How big is a 168 tooth flywheel?

Disc Diameter: 14.125 in.

How do I know what size flywheel I need?

To know what size flywheel you need, you must determine your engine's specifications, such as its balance and crank flange bolt pattern, and then measure the current or required dimensions for applications like industrial engines. For industrial use, you need to measure the pilot bore (K dimension) and pilot bearing bore (O dimension) to find the SAE size. For performance or restoration builds, identify the engine's specific characteristics, like bolt count and ring gear tooth count, to match the correct flywheel. 
For industrial engines

• Measure the flywheel drive ring pilot bore (K dimension): Measure across the inside of the pilot bore where the drive ring bolts. Note the measurement for both options if dual drillings exist.
• Measure the pilot bearing bore (O dimension): Measure across the widest point inside the pilot bearing bore. You can use a tape measure or mark the widest points on paper and measure the distance between the marks.
• Consider drivetrain applications: Since different pilot bearing options exist, both the K and O dimensions are crucial for matching the flywheel to other drivetrain components.
• Refer to SAE standards: Once you have these measurements, you can determine the correct SAE size by comparing them to the official SAE standards for industrial engines. 

You can watch this video to learn how to measure the SAE flywheel size of an industrial engine: 45sPalmer Johnson Power SystemsYouTube · Jun 16, 2023
For automotive engines

• Identify engine balance: Determine if your engine is internally or externally balanced. This is a critical factor in selecting the correct flywheel. 
• Check the crank flange bolt pattern: The number of bolts and their arrangement on the crankshaft flange are specific to the engine and will dictate the bolt circle on the flywheel. 
• Count the ring gear teeth: The number of teeth on the ring gear is a key identifier. For example, some GM LS/LT engines use a 168-tooth gear, while older engines have different counts. 
• Look for other specifics: Consider if the engine has an extended crank flange or a specific displacement. For example, Ford modular engines are typically internally balanced with a 164-tooth ring gear, but some variations exist. 

For performance or restoration projects

• Determine your performance goals: The application, such as drag racing, road racing, or daily driving, will determine the best material and weight. Heavier flywheels provide more stability, while lighter ones improve throttle response. 
• Consider flywheel material: Modern options like billet steel are stronger than older cast iron flywheels, which is important for high-horsepower applications. 
• Match the flywheel to the engine: Ensure the new flywheel is compatible with your engine's characteristics, including its balance and crank flange bolt pattern. 
• Check the condition of the old flywheel (if applicable): If resurfacing is needed, check that the flywheel is not too thin or that the centering lip has not exceeded its wear limit. 

What is the difference between a 157 and 164 tooth flywheel?

If it's a 157 tooth, you need the so called "automatic" starter period. If it's 164, you need the "manual" starter. The difference between the automatic and manual starter is the automatic is for all 157 tooth flywheels and the drive gear sticks out about 3/8" more the the 164 tooth starter drive.

What is the difference between a 153 tooth and 168 tooth flywheel?

The critical item to match up here will be the starter A 153-tooth flywheel always uses the straight bolt pattern starter, while the 168-tooth flywheel will use the angle bolt pattern starter.