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Our ZZ502 received a complete rebuild before initial testing could begin. JMS Racing Engines freshened up the crate motor by giving attention to the bores by opening them from 4.470 inches to 4.500 inches (0.017-inch overbore), added new oversized KB pistons, rings, and rod and main bearings, but utilized the same ZZ502 forged rods and crankshaft. COMP supplied the XR288HR camshaft (0.521/0.540-inch intake/exhaust lift and 236/242 intake/exhaust duration at 0.050 inch on a 106 lobe center) and lifters. The pair of aluminum crate cylinder heads was then upgraded with higher rate, 347 lb/in dual springs.