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17802825 - COPO LS 427 425hp Crate Engine

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The COPO 427 for A Stock competition uses the large-bore cylinder block and high-flow cylinder heads of the LS7 engine and complements them with a high-compression rotating assembly to deliver big power from its large displacement. Its lightweight aluminum block and heads revive the spirit of the original ZL-1 all-aluminum 427 big-block that helped forge the COPO legacy in 1969.


  • Displacement: 427 cu in (7.0L)
  • Compression Ratio: 13.5:1
  • Cylinder Block: LS7 cast aluminum
  • Bore x Stroke (in): 4.125 x 4.100
  • Crankshaft: Forged steel
  • Connecting Rods: Forged steel
  • Pistons: Forged dome
  • Cylinder Heads: LS7 aluminum
  • Induction: Natural
  • Intake Manifold: Holley
  • Camshaft Type: Hydraulic roller
  • Camshaft Lift (int./exh.): .595/595-inch

  • Chevrolet Performance LS7 aluminum block
  • 4.125" bore x 4.00" stroke
  • Static compression ratio - 13:1 nominal
  • Callies 5140 crankshaft
  • Callies 4340 H-beam rods
  • 6.100" C-C length
  • .928" pin bore diameter
  • Clevite H-Series heat-treated tri-metal rod and main bearings
  • Mahle 2618 alloy forged domed pistons
  • Graphal coating
  • Hard-anodized top ring groove
  • Friction-coated skirts
    Mahle .043" x .043" x 3mm piston rings
  • Ductile iron top with radius molybdenum face
  • Plain cast iron tapered 2nd
  • Chrome-plated oil rails with low-tension expander
    Chevrolet Performance steel billet hydraulic roller camshaft
  • Duration — 233°/276° @ .050" lift
  • Theoretical valve lift — .630"/.630"
  • Lobe centers — 107°

    Chevrolet Performance "Ceramic Ball" high-rpm hydraulic roller tappets
    3/8" diameter LS7 pushrods
    1.8:1 ratio LS7 rocker arms with roller trunions
    PSI "Max Life" beehive valve springs
    Hardened steel spring seats
    Lightweight steel retainers
    Fully CNC'ed aluminum cylinder heads — based on LS7
    275 cc nominal intake port volume
    89 cc nominal exhaust port volume
    70 cc nominal combustion chamber volume
    Del West titanium intake valves — 2.205" head diameter x 7mm stem
    Lightweight sodium-filled exhaust valves — 1.615" head diameter x 7mm stem
    Fel-Pro Performance multi-layer steel head gaskets with raised cylinder sealing bead
    Internal wet sump oil pump
    Deep-sump cast aluminum oil pan —
    6-quart capacity
    SFI-approved damper
    Billet electric water pump
    Chevrolet Performance/Holley "Hi Ram" intake manifold
    Whipple billet throttle body — 102mm blade


  • 42 lb/hr @ 58 psi with EV6/USCAR connector

    Cable-actuated throttle
    Production LS7 ignition coils
    Production LS7 secondary wires
    GM sensors

  • Application List


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    • 500.0 lbs.
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