Racing Flag

PARTS INTENDED FOR COMPETITION USE ONLY.
Click for more details.

Racing Flag

PARTS INTENDED FOR COMPETITION USE ONLY.
Click for more details.

BIG-BLOCK ZL1 ALUMINUM BLOCK

12370850

LS7 7.0L CORVETTE BARE BLOCK

Chevrolet Performance Big-Block ZL1 Aluminum Engine Block Lifter Valley View
Chevrolet Performance Big-Block ZL1 Aluminum Engine Block Top Front View
Chevrolet Performance Big-Block ZL1 Aluminum Engine Block Top Rear View
Chevrolet Performance Big-Block ZL1 Aluminum Engine Block 2-Piece Rear Main Seal View
Chevrolet Performance Big-Block ZL1 Aluminum Engine Block 4-Bolt Mains View
  • 4.240” finished bore
  • 4.300” max bore
  • 4.375” max stroke  
  • Use sleeve P/N 12480035
  • 2-piece rear main seal
  • Uses Mark IV front timing cover
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Mark Allen’s beautiful 1967 Camaro RS/SS is powered by an LT4 crate engine.

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A GM ASEP Technician Inspecting a Chevrolet vehicle

Bring Us Your Talent

GM ASEP technicians can earn their degree in as little as 2 years, kick-starting a fulfilling career in the automotive industry. The program aims to guide you every step of the way.

Learn More

Learn More
Mark Allen’s beautiful 1967 Camaro RS/SS is powered by an LT4 crate engine.

The BLOCK

Visit TheBLOCK.com for a behind-the-scenes look at the world of Chevrolet Performance from an enthusiast's point of view.

Learn More

Learn More
Four Chevrolet Camaro Sports Cars Parked on Display in a Showroom

Connect With Chevrolet Performance

Connect with Chevy Performance.
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VISIT OUR BRANDS FOR YOUR OE NEEDS

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Unless specifically noted to the contrary herein, vehicles equipped with Chevrolet Performance parts that are emissions-related may not meet U.S., Canadian, and state and provincial laws and regulations relating to motor-vehicle emissions. These parts are designed and intended for use in vehicles operated exclusively for competition: in racing or organized competition on courses separate from public streets or highways. Visit www.chevroletperformance.com/emissions for more details.
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Unless specifically noted to the contrary herein, vehicles equipped with Chevrolet Performance parts that are emissions-related may not meet U.S., Canadian, and state and provincial laws and regulations relating to motor-vehicle emissions. These parts are designed and intended for use in vehicles operated exclusively for competition: in racing or organized competition on courses separate from public streets or highways. Visit www.chevroletperformance.com/emissions for more details.