Fully Balanced Small Block Chevy 421 assembly with Wiseco Racing Forged Pistons 4.155 bore. -16cc RD D-CUP Dish (58cc= 11.36, 64cc=10.67, 68 cc=10.25, 72cc= 9.87) upgraded rings to steel rings gaped for up to 300 hp shot of nitrous, Scat 4340 Forged 3.875 stroke Crankshaft polished & 6.0 Scat H-Beam Rods with ARP-2000 Rod bolts, PRW SFI Racing Damper. Also, including Double Roller timing chain and cover. Engine only had a few 1/8 mile 150 hp nitrous passes and 400 miles. Fits SBC 2PC rear main seal block with 400 mains. Engine components only removed to upgrade to a F1R Cog driven Procharger and went with the big block Chevy snout.