Hypereutectic Dome Piston Set, 4.030" Bore

The KB Performance Claimer Series hypereutectic pistons are engineered for Small Block Chevy engines requiring a 4.030 in bore. This set of eight pistons features a dome design with +4.00 cc compression volume and 5/64 x 5/64 x 3/16 in ring grooves. Constructed from a high-silicon aluminum alloy, these pistons are lightweight to enhance throttle response and RPM changes while offering strength for high compression and temperatures. Modern piston design is employed, placing the top ring higher for improved performance. This higher ring placement results in increased operating temperatures, necessitating slightly larger ring end gaps. The product documentation provides a method for calculating the proper top ring end gap by multiplying the bore size by a specific gap factor (e.g., 0.0065" for Street Normally Aspirated engines). Installation recommendations include retarding ignition timing by 2-4 degrees, as these "Claimer piston engines" will require less total ignition timing for optimal performance. This precise timing is crucial for achieving consistent results across all cylinders by ensuring equal air flow, fuel mix, quench, chamber temperature, swirl, and compression. These pistons are designated as Original Equipment (OE) replacement for specific applications: Trucks from 1969-1978, Passenger Cars from 1969-1970, and Corvettes from 1990-1991. It is explicitly stated that for all other years, these pistons are not legal for sale or use on pollution-controlled vehicles.