Adjusting the Cam and Overhead on a Cummins ISX15 CM570

[MikePhua]

Precision Tools Matter for Injector Adjustment
The Cummins ISX15 Signature CM570 engine, introduced in the early 2000s, is known for its robust performance in heavy-duty applications. With horsepower ratings ranging from 400 to 600 hp and torque outputs exceeding 2,050 lb-ft, it remains a popular choice among owner-operators and fleet managers. One of the key maintenance tasks for this engine is the overhead adjustment, which includes setting valve lash and injector cam clearance. This procedure ensures proper combustion timing, fuel delivery, and valve operation.
For injector adjustment, Cummins specifies the use of a dial-type torque wrench, which provides visual feedback on torque application. This is critical because the injector cam follower must be torqued precisely to avoid over-fueling or misfire. Some technicians ask whether a digital torque adapter can be used instead. While digital adapters offer convenience and accuracy, they often lack the tactile feedback and sweep visibility of a dial wrench, which is especially useful when working in confined engine compartments.
Understanding the CM570 Overhead Procedure
The CM570 uses a single overhead camshaft with rocker arms actuating both intake and exhaust valves, as well as the injector plunger. The adjustment sequence typically follows the firing order: 1-5-3-6-2-4, with the engine rotated to top dead center (TDC) for each cylinder. At TDC, the valves for that cylinder are closed, allowing accurate lash measurement.
Recommended clearances:

• Intake valve lash: 0.014 in
  
• Exhaust valve lash: 0.027 in
  
• Injector cam lash: torque to 72 in-lbs using dial wrench
  

The injector adjustment is not a lash setting but a torque preload. This ensures the injector plunger is correctly seated without excessive force, which could damage the cam lobe or injector body.
Tips for First-Time Adjustments

• Watch a seasoned technician perform the procedure before attempting it solo
  
• Use a feeler gauge set with long blades for better reach
  
• Mark the crankshaft pulley with TDC positions to simplify rotation
  
• Keep a logbook of adjustments with date, cylinder readings, and torque values
  
• Always verify torque wrench calibration before use
  

One operator in Australia shared that he planned to observe the procedure on his own truck before attempting it himself. This is a wise approach, especially for those unfamiliar with Cummins overhead setups.
Common Mistakes and How to Avoid Them

• Using a click-type torque wrench for injector adjustment: This can lead to over-torquing and injector damage
  
• Skipping cylinder verification: Always confirm TDC with valve movement, not just timing marks
  
• Neglecting rocker arm inspection: Worn or loose rockers can throw off lash readings
  
• Incorrect firing order: Following the wrong sequence can result in poor engine performance
  

Conclusion
Adjusting the cam and overhead on a Cummins ISX15 CM570 requires precision, patience, and the right tools. While digital torque adapters may seem convenient, a dial-type torque wrench remains the preferred method for injector adjustment due to its visual accuracy. For those new to the procedure, observing a professional and studying the engine’s behavior cylinder by cylinder is the best way to build confidence and ensure a successful outcome.