Product information: 551275 Cylinder Head Dowel Alignment Pins Compatible with Gen 3 Gen 4 Gen 5 LS/LT Series Engines, 4-pack. Dimensions: The dowel pin has a diameter of 0.65 inches and a length of 0.58 inches Product function: 1. Precise Alignment: Ensures precise alignment between the cylinder head and the engine block during installation, preventing sealing issues caused by misalignment. Precise alignment helps ensure the correct sealing of the cylinder head gasket, preventing coolant, oil, and combustion gas leaks. 2. Improved Engine Performance: Precise alignment ensures the combustion chamber is correctly positioned, thereby enhancing combustion efficiency and improving engine performance and fuel efficiency. 3. Preventing Mechanical Damage: Avoids engine mechanical failures caused by misalignment, extending the engine's lifespan Installation Steps: 1. Before installation, ensure that the engine is disconnected from power and in a stable condition. 2. Locate the dowel pin holes on the engine block and insert the new dowel pins into the holes. 3. When installing the cylinder head, ensure that the dowel pins guide the cylinder head into correct alignment. 4. After installation, check that the cylinder head is properly aligned and that all connections are secure Compatibility: Suitable for Gen 3, 4, and 5 LS/LT series engines, including LT, LSX, LS1, LS2, LS3, LQ4, LQ9, LS6, L92, L99, L33, LR4, L82, L83, L84, L86, L87, LT1, L8B, and more Precautions: Safety: Always ensure the engine is disconnected from power during the operation to avoid the risk of electric shock. Refer to the Manual: If possible, refer to the engine's user manual or the manufacturer's compatibility list After-sale service: We will provide you with quality and performance guarantees. If you have any questions about our products, please feel free to contact us. We are happy to assist you and enhance your shopping experience