Jeep 4.0 AMC 4.2(swap) CNC "IRON" Competition Cylinder Head(91-06)
Jeep 4.0 AMC 4.2(Swap)"CNC" aftermarket casting "Competition LS converted Cylinder heads". These heads are CNC'd then meticulously built from the ground up with all the upgrades and best parts such as: 2.055"/1.60" Stainless Steel 8mm valves, competition valve job, beehive springs w/steel retainers and locks, upgraded Viton positive locking valve seals, custom machined spring seats for added cam lift capacity up to .600" lift, This is our all new port design, all fully assembled and ready to bolt on. We recommend this head for Strokers, Boosted applications, or 'Hot' upgraded 4.0/4.2 engines with upgraded cam, intake and header with increased rpm potential to reap the rewards.
***These heads depending on application and supporting mods will increase power levels from 25-75HP Naturally Aspirated and more with Forced Induction, with much added efficiency from the crack of the throttle to peak rpm. Your exhaust note and tone will change(Deeper/Louder) with the addition of these heads due to size and flow characteristics***
They are based off of a 99-06 model design with coil pack mounts and a machined front idle pulley if needed. The exhaust port arrangement has been moved to allow them to be used for all prior 4.0 head applications and header designs. You can use the TUPY or Stock style gasket, place your int/exh gasket order based on the header design.
We also recommend a complimenting cam package, ported Intake, 60mm and larger throttle body, fueling upgrades(injectors/tuning/500CFM & up carb) and header collector size of 2.5" or bigger, depending where you want your power band.
***Lead time once order is placed for heads is around two weeks unless we have them ready on the shelf. As of 10/01/25***