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Manley Severe Duty Series Stainless Steel Valves 12803-8 VALVE-BBC S/D 1.940

SKU: MAN12803-8

Valves

Manley Severe Duty Series Stainless Steel Valves 12803-8 VALVE-BBC S/D 1.940

SKU: MAN12803-8

Valves
A$599.23
Available from MFR. This item is available from the manufacturer's distribution centre. The dispatch timeframe shown is an estimate based on historical order processing and release times for this part. This item is not held in our own warehouse, and actual dispatch timing may vary depending on manufacturer workload and logistics at the time of ordering.
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Description

Manley Severe Duty® Valves deliver the ultimate in strength, reliability, and high-performance durability. Engineered for extreme gasoline engine temperatures, these valves are crafted from exclusive materials (XH-428 for exhaust and NK-844 for intake), offering unmatched tensile strength compared to competitive alloys. In fatigue testing at 40,000 psi and 1400°F, Manley exhaust valves endured 100 million cycles, while competitors failed after just 100,000, proving a 1,000× longer fatigue life. Each valve features chrome stems, hard tips, and swirl-polished underheads with fully machined combustion faces for superior airflow, efficiency, and wear resistance. Built for those who demand race-winning strength and precision, Manley Severe Duty® Valves set the industry standard for performance and endurance.

Part Type

Engine Exhaust Valve

Data: v4.2 - Upd: 2026-10-14 10:04:35

Features

  • Chrome stems and hard tips enhance durability
  • Exotic alloys for superior tensile strength, reliability, and longevity
  • Proven fatigue strength for extreme performance
  • Swirl polishing and machined faces improved airflow/optimized efficiency

Specifications

Product Attributes - Brand
Manley
Product Attributes - Manufacturer's Part Number
12803-8
Product Attributes - Part Type
Valves
Product Attributes - Product Line
Manley Severe Duty Series Stainless Steel Valves
Product Attributes - UPC
807298016184
Product Attributes - Valve Position
Exhaust
Product Attributes - Exhaust Valve Head Diameter (in.)
1.940 in.
Product Attributes - Exhaust Valve Head Diameter (mm)
49.276mm
Product Attributes - Exhaust Valve Stem Diameter (in.)
0.311 in.
Product Attributes - Exhaust Valve Stem Diameter (mm)
7.89mm
Product Attributes - Exhaust Overall Valve Length (in.)
5.422 in.
Product Attributes - Exhaust Overall Valve Length (mm)
137.719mm
Product Attributes - Undercut Stem
No
Product Attributes - Swirl-Polished
Yes
Product Attributes - Valve Tip Length (in.)
0.250 in.
Product Attributes - Valve Tip Length (mm)
6.350mm
Product Attributes - Valve Material
Stainless steel
Product Attributes - Lock Groove Quantity
1-groove beadlock-style
Product Attributes - Lock Groove Style
Beadlock
Product Attributes - Approximate Weight (g)
109
Product Attributes - Valve Head Style
7 degree dish
Product Attributes - Valve Seat Width (in.)
0.100 in.
Product Attributes - Quantity
Sold as a set of 8.

Reference Information

Brand Name/s Manley Performance
StreetFX SKU man12803-8
SFX Item ID 4933664
Supplier Item Code 4933664
Manufacturer SKU 12803-8
Manufacturer UPC 807298016184

Compatibility

Application Data
  • Valve FitmentSearch by engine
    MakeCHEVROLET
    Beginning Year1965
    Ending Year1970
    Engine TypeV8
    Engine Size6.5L/396
    Engine FamilyChevy big block Mark IV
    Valve Installed LengthStock
    Cylinder Head TypeStock configuration
  • Valve FitmentSearch by engine
    MakeCHEVROLET
    Beginning Year1966
    Ending Year1969
    Engine TypeV8
    Engine Size7.0L/427
    Engine FamilyChevy big block Mark IV
    Valve Installed LengthStock
    Cylinder Head TypeStock configuration
  • Valve FitmentSearch by engine
    MakeCHEVROLET
    Beginning Year1970
    Ending Year1972
    Engine TypeV8
    Engine Size6.6L/402
    Engine FamilyChevy big block Mark IV
    Valve Installed LengthStock
    Cylinder Head TypeStock configuration
  • Valve FitmentSearch by engine
    MakeCHEVROLET
    Beginning Year1970
    Ending Year1990
    Engine TypeV8
    Engine Size7.4L/454
    Engine FamilyChevy big block Mark IV
    Valve Installed LengthStock
    Cylinder Head TypeStock configuration
  • Valve FitmentSearch by engine
    MakeCHEVROLET
    Beginning Year1991
    Ending Year1995
    Engine TypeV8
    Engine Size7.4L/454
    Engine FamilyChevy big block Gen V
    Valve Installed LengthStock
    Cylinder Head TypeStock configuration
  • Valve FitmentSearch by engine
    MakeCHEVROLET
    Beginning Year1996
    Ending Year2000
    Engine TypeV8
    Engine Size7.4L/454
    Engine FamilyChevy big block Gen VI
    Valve Installed LengthStock
    Cylinder Head TypeStock configuration

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