Engineered for high-RPM drag race engines, Ultra 18ø 250 cylinder heads provide more horsepower out-of-the box than fully prepped OEM-style 23ø heads.. Aluminum head includes CNC-profiled combustion chambers and competition-ported runners for maximum flow. Head accepts most 18ø intake manifolds, headers, and related components. Requires offset shaft-mounted rocker arms and mechanical roller camshaft with offset intake lifters.
- Cylinder Head Style:
- Assembled
- Cylinder Head Material:
- Cast aluminum
- Cylinder Head Finish:
- Natural
- CNC-Machined Combustion Chamber:
- Yes
- Combustion Chamber Volume (cc):
- 56cc
- Combustion Chamber Style:
- Heart
- CNC-Machined Intake Runner:
- Yes
- Intake Runner Volume (cc):
- 250cc
- Intake Port Shape:
- Rectangular
- Intake Port Location:
- Raised
- Intake Valve Angle:
- 18 degree
- CNC-Machined Exhaust Runner:
- Yes
- Exhaust Runner Volume (cc):
- 100cc
- Exhaust Port Shape:
- Oval
- Exhaust Port Location:
- Raised
- Exhaust Valve Angle:
- 18 degree
- Intake Valves Included:
- Yes
- Intake Valve Diameter (in.):
- 2.150 in.
- Exhaust Valves Included:
- Yes
- Exhaust Valve Diameter (in.):
- 1.600 in.
- Valve Type:
- Stainless
- Maximum Valve Lift (in.):
- 0.700 in.
- Valve Springs Included:
- Yes
- Valve Spring Type:
- Dual W/Damper
- Outside Diameter of Outer Spring (in.):
- 1.560 in.
- Valve Guides Included:
- Yes
- Valve Guide Material:
- Bronze
- Valve Seats Machined:
- Yes
- Valve Seat Material:
- Ductile iron
- Valve Seat Machine Style:
- 3-angle
- Retainers Included:
- Yes
- Retainer Material:
- Titanium
- Valve Stem Seals Included:
- Yes
- Valve Stem Seal Style:
- Viton Positive stop
- Locks Included:
- Yes
- Lock Style:
- 10 degree
- Camshaft Style:
- Solid roller
- Spark Plug Style:
- Angled
- Guideplates Included:
- No
- Guideplate Pushrod Size:
- N/A
- Rocker Arm Studs Included:
- No
- Rocker Arm Nut Thread Size:
- N/A
- Accessory Bolt Holes Drilled:
- Yes
- Valve Cover Mounting Style:
- Perimeter bolt
- Heat Crossover:
- No
- Steam Holes Drilled:
- No
- Oiling Style:
- Through pushrod
- Machined for O-Ring:
- No
- Quantity:
- Sold individually.
- Notes:
- Requires Jesel or T&D shaft mount rocker arm system, offset 0.550 in. for the intake side and 0.220 in. for the exhaust side. Will also need special 18 degree intake manifold and custom-built headers.
- Make:
- Chevrolet
- Engine Family:
- Chevy small block Gen I
- Engine Sizes:
- 4.9L/302-5.7L/350
- Years:
- 1962-1986
