AFR 12° LS3 Mongoose Head, 260cc, Set/2

AFR’s 260cc LS3 “Mongoose” heads feature 100% CNC ported intake, exhaust and chambers using our advanced engineering and flow techniques to produce the ultimate Rectangle Port head available today. Featuring A356 aluminum castings, titanium retainers and the highest quality components, throughout. They’re designed for 4.000 or larger bore applications up to 454 CI, operating up to 7000 RPM. Emmisons legal for 2008 to 2015 vehicles under CARB #D-250-5.

Stock GM Rocker Arms - GM Rocker Arms are not designed/engineered to accommodate aftermarket cams or higher spring pressures. At a minimum AFR recommends using Bushing Trunion Kit. Other available options are aftermarket kits from Yella Terra, Scorpion,or Comp Cams. Without the proper parts you will experience accelerated guide wear.


Boosted/Nitrous Applications - We strongly recommend considering Inconel exhaust valves and AFR's optional heavy duty intake valve for power adder applications. Since boosted or nitrous oxide applications accelerate RPM quickly, additional spring pressure is required. We strongly recommend upgrading your valve springs or increasing your valve spring pressures since boost pressure on the valve reduces spring tension. For example, 15lbs boost on a 2.125 OD valve reduces the springs closed seat pressure by approximately 40-45lbs.