Alternative Firing Order Duramax Drag Racing/Sled Pulling #9200AF

Extend the life of your crankshaft by changing the firing order of your engine.

The Alternative Firing Order (AF) camshaft was invented at SoCal Diesel in 2011. It is now the industry standard for Duramax engines.

The OEM firing order ends with cylinder 3 and begins with cylinders 1 and 2. The result is a 3-1-2 hit to the crankshaft. Duramax cranks have a tendency to break right behind the first rod throw at the intersection of the second main journal, right where the 3-1-2 hit would stress the crankshaft the most. Coincidence? We think not.

After carefully researching the different firing orders available to a V-8 engine, SoCal Diesel was the first to implement this "Alternative Firing Order" camshaft for the Duramax engine. In moving cylinders 3, 1 and 2 away from each other, we have significantly extended the abuse the crankshaft can withstand.

Swapping a few pins in the wiring harness will insure the ECM sends the injector signal to the correct cylinder. Wiring diagrams and instructions are included with every purchase.

• Requires .075 piston valve pockets.
• Works well from 2500-5200 rpm.
• Requires a high stall converter.
• Valve Lash .012/.012
• We recommend the use of LLY or later lifters. Do not use LB7 lifters.

• The camshaft is an integral part of your engines breathing characteristics. 
• The camshaft lobe profiles need to be carefully matched to the rest of the engine components in order to achieve maximum performance for any given application. 
• We have designed profiles to meet many different applications that include dedicated Drag Racing and Sled Pulling. 

Valve Adjustment Procedure 

• 1)     Rotate the engine and adjust one cylinder at a time.
• 2)     When the exhaust valves just begin to open, adjust the intake.
• 3)     When the intake valves are just past maximum lift, adjust the exhaust.

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