24502572 - DRCE Bowtie Chevy Big Block - 4.500"-4.700" Bore, 9.500" Deck, 2.75" Mains, 4 Bolt Main, Siamesed Bores

This Chevrolet Performance Parts/DRCE (Drag Race Competition Engine) "2" bare block is a redesigned Old's DRCE block. This block was designed for competition in 500ci in Winston NHRA Pro Stock Drag Racing or similar type usage. The main differences between the Old's DRCE and GMPP "2" blocks are the camshaft has been raised to 5.750", the deck height is a 9.525" and can be reduced to approximately 9.000", the distributor hole has been moved rearward on the block, and the overall weight has been reduced approximately 11 pounds. The cylinder bore centerline spacing has been increased from 4.840" to 4.900", the maximum legal bore spacing allowed for NHRA Pro Stock competition. With the new bore spacing of 4.900" it will allow the use of 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 4.500" diameter. Maximum recommended bore diameter is 4.700". New elliptical siamesed cylinder barrels maximize wall thickness on the major and minor thrust axes. This allows lighter weight piston and rod combinations and improves carburetor, manifold port alignment with Pro Stock type induction systems. This block's cam tunnel will accommodate a 2.166" cam bearing. Other improvements are #2 and #4 main bearing bulkheads are relocated .060" to distribute crankshaft loads evenly. The lifter bosses have been replaced with 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, so the engine builder can accommodate Pontiac Super Duty, Oldsmobile DRCE, or Chevrolet bolt patterns. The rear flange has a hybrid bolt pattern that accommodates Olds, Pontiac or Chevy bellhousings. they use new 4-bolt 8620 steel main bearing caps with spayed outer bolts to main bearing bulkhead durability and resist bearing bore distortion under high load. The oil pan rails have been spread .400" per side to provide room for longer stroke crankshafts. The starter motor can be mounted on either side of the GMPP/DRCE "2" block. Technical Notes: This high-strength iron block has brinell hardness of 210 to 230 and requires a camshaft with distributor gear behind the rear bearing. The balance of parts to complete this engine are Chevrolet big-block (water pumps, crank, cam, balancers, flywheel, and manifolds). This block is cast with the GM Performance Parts logo on it.