GM Performance Engine Block, Cast Iron, 4-Bolt Mains, 4.500 in. Diameter Bore, 2-Piece Rear Main Seal, Chevy, DRCE 2, Each (PART #GMP-24502572)

Want to go NHRA Pro Stock racing? Make sure you get one of these GM Performance DRCE 2 engine blocks to build your high-revving competition engine. These GM Performance DRCE 2 engine blocks have been newly redesigned Oldsmobile DRCE blocks, and they're designed for competition in 500 c.i.d. NHRA Pro Stock drag racing or similar-type usage. GM Performance DRCE 2 engine blocks feature a relocated camshaft that has been raised to 5.750 in. The deck height is 9.525 in. and can be reduced to approximately 9.000 in., the distributor hole has been moved rearward on the block, and the overall weight has been reduced by approximately 11 lbs. The cylinder bore centerline spacing has been increased to 4.840 in., which is the maximum legal bore spacing allowed for NHRA Pro Stock competition. The new bore spacing of 4.900 in. will allow the use of a big bore with short stroke piston and crankshaft combinations to enhance performance. The increase in cylinder bore spacing reduces valve shrouding and permits the use of larger valves to improve airflow. The semi-finished cylinder is bored to a 4.500 in. diameter with a maximum 4.700 in. recommended bore diameter. New elliptical siamesed cylinder barrels maximize wall thickness on the major and minor thrust axes, allowing for lighter-weight piston and rod combinations, and improve carburetor and intake manifold port alignment with Pro Stock type induction systems. The GM Performance DRCE 2 engine blocks' camshaft tunnel will accommodate a 2.166 in. cam bearing and relocated main bearing bulkheads to distribute crankshaft loads evenly. The lifter bosses have been replaced with a solid bar, and the lifter holes are not drilled to allow engine builders to position them for their own valvetrain geometry. The head bolt holes are not drilled to allow engine builders to accommodate Pontiac, Oldsmobile DRCE, or Chevrolet bolt patterns. The rear flange has a hybrid bolt pattern that accommodates Oldsmobile, Pontiac, or Chevrolet bellhousings. The oil pan rails have been spread .400 in. per side to provide room for longer-stroke crankshafts, and the starter motor can be mounted on either side.