The new style became the exclusive unit in most 2009 and newer engines.
• Original (old style) GM Part #12585994: 2007?2008 (uses cam core 156?family)
•Current (new style) GM Part #12606358: 2007-2009 and newer engines (use cam core 189?family).
The difference in the camshaft core is the pin to centerline position. The difference in the pin between 156 and 189 works out to 13 degrees cam retard (if a 156 is used where a 189 is required).
– Tech Bulletin courtesy of Comp Cams 
From the high-performance powerplants propelling Top Fuel dragsters to the subdued engines found in family sedans and grocery getters, each crank must be tailored to, and appropriate for, its specific application.
We know a crankshaft plays a critical role in an engine’s performance, converting reciprocating motion into rotary motion while serving as the backbone of the entire system. It must be strong enough to withstand the continuous pounding of rods and pistons, yet possess enough elasticity to absorb vibrations and flex, albeit slightly, when needed.
I always keep a pair of needle nose pliers and a small, straight screwdriver in my blast cabinet to hold small parts when blasting.
Submit your Shop Solution at [email protected].
Jeff McCord of LinCo Diesel Performance walks you through degreeing a camshaft and checking valve-to-piston clearance.
After a customer wanted a Steve Morris Engines’ SMX in an LS version, Steve saw the upside and potential in the market, and a challenge to build a better LS.
The valve job ensures the mating surfaces of the valves and the seats properly control the air/fuel mixture.
When it comes to improving horsepower and rpm, airflow has a lot to do with it, and it seems the job is one that’s never finished.
Head gaskets have one of the toughest job in an engine, and now we’re pushing them harder than ever, making it easier to expose the slightest weakness.
Right away, engine builders knew it was special.
