Jesel belt drive systems are components used in internal engine applications. These systems utilize a belt and pulley arrangement to drive the engine’s camshaft. The available documentation provides installation guidance, maintenance recommendations, and troubleshooting information for these systems. This article details these aspects, drawing solely from the provided materials.
System Components and Overview
Jesel belt drive systems are designed for use with various engine configurations. The documentation highlights the importance of proper installation and maintenance to ensure optimal performance and longevity. The systems incorporate features intended to improve valvetrain stability and reduce wear. Specific components addressed in the documentation include the drive belt, pulleys, cam adapters, and lifters. The documentation notes that Jesel offers undersized and oversized belts to accommodate variations in component dimensions and valvetrain setup.
Installation Procedures
Proper installation is critical for the correct operation of a Jesel belt drive. The documentation emphasizes the need to test fit all components before final assembly, particularly when using aftermarket engine blocks. Modifications to the engine block may be necessary to ensure adequate clearance for the belt drive cover. The documentation recommends using a degree wheel to accurately set cam timing, as alignment dots on the pulleys are intended for general reference only.
When installing the lower pulley, the documentation specifies that the seals used in Jesel belt drives are Teflon® coated and should be installed dry. Applying oil to the seal area is not recommended. For two-piece cam drives, cam timing is adjusted by loosening the upper pulley nuts and rotating the crankshaft. Solid upper pulley drives require removal of the upper pulley for timing adjustments. The documentation cautions users to verify piston-to-valve clearance before altering cam timing.
Camshaft Endplay and Backlash
Maintaining appropriate camshaft endplay is crucial for lifter health and oil distribution. The documentation recommends approximately 0.010” of camshaft endplay for belt drives with adjustable thrust plates. Excessive endplay can lead to premature lifter failure, while insufficient endplay may restrict oil flow to the thrust surfaces. Jesel offers cam adapters with needle bearing thrust assemblies, which can operate with as little as 0.001” of endplay.
Belt backlash, inherent to the Gates HTD® timing belt profile, is considered normal within a range of 2° to 4° under a fully assembled valvetrain. Backlash exceeding 4° may necessitate the use of an undersized belt or an oversized upper pulley. Jesel stocks both undersized and oversized belts for various applications.
Belt Maintenance and Replacement
The documentation provides specific recommendations for belt replacement intervals based on engine application. For V8 drag race engines, the belt should be replaced after approximately 250 passes. For oval track or endurance racing applications, the belt should be changed whenever the engine is refreshed. If an engine failure occurs that could have temporarily locked up the rotating assembly, the belt should be replaced as a precautionary measure.
The documentation also addresses belt cleaning. The belt can be cleaned with mild soap and water detergents, but harsh chemicals such as lacquer thinner, brake cleaner, or mineral spirits should never be used. If the belt becomes saturated with engine oil, replacement is recommended.
Lifter Considerations
Jesel lifters incorporate an internal locking pin to secure the axle to the body, eliminating the need for external snap rings or spirolocs, which can occasionally fail and cause engine damage. The documentation notes that most lifters purchased after June 2007 can be fully rebuilt at Jesel’s Lakewood, NJ facility. Lifters purchased prior to June 2007 are not recommended for rebuilding due to design changes.
The documentation does not provide a fixed time interval for lifter replacement, as this depends on factors such as the operating environment, oil used, and valvetrain stability. However, Jesel offers lifter inspection services to assess their remaining lifespan.
Rocker Arm Geometry and Valve Lash
Jesel’s Low Pivot geometry is designed to minimize roller travel distance under high spring loads, reducing the potential for roller skidding and valve guide wear. This geometry utilizes a portion of the rocker arm arc that produces a minimal sweep pattern from half to full lift. Proper valve lash adjustment is also critical. The documentation outlines a procedure for setting valve lash, rotating the engine to specific points in the valve opening cycle and adjusting the lash accordingly.
The documentation recommends using a torque wrench when setting valve lash, with a torque setting of 25 Lbs-Ft for typical 3/8-24 cup or ball style adjusters. Overtightening the adjuster nut can stress the threads in the rocker body, leading to premature failure.
Addressing Common Issues
The documentation addresses several frequently asked questions. It clarifies that the crank seal should not be oiled before installing the lower pulley. It also acknowledges that modifications to the engine block may be necessary to accommodate the belt drive cover, particularly with aftermarket blocks. The documentation provides guidance for situations where the engine block has been aligned bored, recommending removal of the dowel pins to allow the cover to self-center.
Shielding and Abrasive Environments
For engines operating in abrasive environments, such as dirt tracks, the documentation strongly recommends shielding the front of the drive to protect the belt and pulley surfaces from damage caused by dirt and debris.
Conclusion
Jesel belt drive systems require careful installation and regular maintenance to ensure optimal performance and reliability. The documentation emphasizes the importance of accurate cam timing, proper camshaft endplay, and appropriate belt replacement intervals. Adhering to these guidelines, along with the specific recommendations provided for lifter maintenance and rocker arm geometry, will contribute to the longevity and efficiency of the valvetrain.