Chevy 350 Vortec Mid-Dress Crate Engine

The ATK HP32M is a Chevy 350 Vortec mid-dress crate engine engineered to deliver 350 horsepower and 400 lb-ft of torque. Built upon an OE roller block with a 4-bolt main and 1-piece seal, this engine is designed for 1996-2000 model years. It features a 350 cubic inch displacement with a 4.040-inch bore and 3.480-inch stroke. The internal components include OE reground crankshafts (external balance at the rear, internal at the front) and 5.7-inch OE powder metal rods. Hypereutectic pistons provide a 9.5:1 compression ratio, working with Moly rings for durability. The camshaft is a hydraulic roller type with specs of 220/224 at 50 thousandths lift and .495/.502-inch lift with a 110 LSA. This mid-dress engine comes equipped with ATK Vortec cast iron cylinder heads featuring 67cc combustion chambers and 1.94-inch intake/1.50-inch exhaust valves, along with stamped steel 1.5 ratio rocker arms. A double-roller timing chain ensures precise valve timing. The engine includes an ATK HP dual-plane intake manifold, an HEI distributor with an iron gear, and an OE long-style water pump. The oil system utilizes a 5-quart rear sump oil pan, which is not compatible with Chevelles featuring steering behind the crossmember, certain Corvettes, and 1962-1967 Chevy II models. It also includes a Melling standard volume oil pump and is internally balanced, with an externally balanced flexplate/flywheel. Recommended components for optimal performance include a Quick Fuel 670 CFM vacuum secondary carburetor with electric choke, a mechanical fuel pump (80-110 GPH), Autolite #605 spark plugs, and 8mm spark plug wires. For operation, use conventional 10W30 non-synthetic oil, a Wix or K&N oil filter, and set timing between 34-36 degrees. Spark plugs should be gapped to .035 inches. The firing order is 1-8-4-3-6-5-7-2, requiring 91+ octane fuel and a stock stall converter. Exhaust should be 1 5/8-inch headers.