Fits: 2001 thru 2016 Chevy Silverado/GMC Sierra 2500HD/3500HD LB7/LLY/LBZ/LMM/LML Duramax Diesel

Carbocore- Carburized & Hardened 8620 steel camshaft cores are produced to AMS 2301 (AQ) standards. The Callies engineering staff can create an unground lobe profile to our exact requirements. Carbocore cams are machined and heat treated entirely in house at Callies. The Carbocore process creates a visually stunning finish and will also hold up better than the Indurocore cams in dirty environments.

The main reason for modifying the Duramax firing order with the camshaft is to relieve stress on the front portion of the crankshaft in higher performance applications. The OEM firing order ends at Cylinder #3 and then continues from the beginning through cylinders 1 and 2. The Duramax Cranks see the most strain and tend to break right behind the first rod throw at the intersection of the second main journal (the snout). We have seen failures on anything from mildly modified daily drivers to max effort trucks. The Duramax engine Harmonics become too stressful on the cranks when getting into the higher RPM ranges and bigger power levels with the OEM firing order. With this DuraStar Alternate Firing Camshaft, cylinders 1, 2, and 3 are moved away from each other to distribute the stress of combustion more evenly and help reduce the abuse to your crankshaft. Duramax engines respond to alternate firing camshafts better than any other diesel on the market. Thanks to the high flow aluminum heads, the right camshaft can increase the Duramax's Head flow considerably. Dyno tests have proven a much broader power curve, increasing HP and Torque through all RPM's making this mod perfect for anything from a daily driver to NHRDA usage.

Notes:

• Great Replacement for tow, street, and strip!
• Stage 1, No Piston Valve Reliefs Needed! Works great at Idle to well past 3800 RPM
• Engine Wiring Harness modifications are required due to the new firing order.
• THE MANUFACTURE, SALE, OFFER FOR SALE, OR INSTALLATION OF THIS PRODUCT IS NOT LEGAL IN CALIFORNIA.

Instructions:

• 2001-2004 LB7
• 2004.5-2005 LLY
• 2006-2007 LBZ
• 2007.5-2010 LMM
• 2011-2016 LML