[TJ-Valderrama]

Spec Culata.

- Made in USA by HESCO
- Virgin 356 Aluminum T-6 heat treated
- Hardened seats & silicon bronze guides
- Direct bolt-on replacement for stock head
- Fits 1991 - 2007 4.0L engines
- Fits all 4.2L engines using 4.0L Intake / Exhaust
- 30-pounds lighter than stock cast iron head
- 5/8" thick deck for increased strength
- 30 HP gain on 4.0L - 50 HP gain on 4.2L
- Lowers CHT & combustion chamber temps
- Reduces detonation from low octane fuels
- Improves NOX emmissions
- Includes performance valve springs
- Rocker bosses will accept stock or roller rockers
- Extra thick runners for porting up to 0.250"
- Extra metal under the springs for oversize springs
- Raised V/C mating surface accomodates rollers
- Enlarged push rod holes simplify cam changes
- All accessory bolt holes (Incl coilpack holddowns)
- Serial Number stamped on each head