Speedmaster 1-286-001-01 H1 SBC 350 4-Bolt Billet Main Bare Engine Block

The Speedmaster H1 engine block represents the ultimate foundation for building a Chevrolet small block 350 engine capable of handling 1,500+ horsepower. Engineered from the ground up as a severe-duty performance block, the H1 is designed to withstand the extreme demands of naturally aspirated, supercharged, turbocharged, and nitrous oxide applications. Whether you're building a street machine or a dedicated race engine, this precision-machined block delivers the strength and reliability required for serious power.

Key Features:

• Premium Class 32B Cast Iron Construction: Manufactured from high-strength Class 32B iron for exceptional durability and heat dissipation under extreme performance conditions
• 4-Bolt Billet Steel Main Caps: All five main caps are CNC-machined from billet steel with the three center caps featuring splayed bolt design for maximum main bearing support and crankshaft stability
• Standard 9.025-inch Deck Height: Maintains compatibility with off-the-shelf small block Chevy components including pistons, connecting rods, and cylinder heads
• 4.000-inch Cylinder Bore: Pre-bored to 4.000 inches with 0.275-inch minimum cylinder wall thickness, allowing safe overboring to 4.185 inches maximum recommended
• 350 Main Bearing Journals: 2.450-inch main bearing size with 2.649-inch main bearing bore configured for standard SBC 350 crankshafts
• Priority Main Oiling System: Features priority main oiling for improved lubrication to main bearings, with provisions for wet sump or dry sump configurations
• Deep Stepped Main Cap Register: Eliminates the need for dowel pins while ensuring precise main cap alignment and retention
• Standard SBC Component Compatibility: Uses standard small block camshaft (1.869-inch cam journals), timing chain, oil pump (0.481-inch shaft), oil filter, and motor mounts
• Precision Pre-Machined: Arrives precision-machined to eliminate the time and expense of blueprinting a stock block or finishing a semi-finished casting
• Competition-Ready Design: Includes provisions for standard mechanical fuel pump, standard-length fuel pump pushrod, and standard SBC lifter bores (0.8427-0.8437 inches)

Specifications: 4.000-inch bore diameter, 9.025-inch deck height, 0.675-inch minimum deck thickness, 2.450-inch main bearing size, 0.005-inch main cap press fit, 10 freeze plugs (1-5/8-inch press-in cup plugs), 2.375-inch cam plug. This is a bare block requiring complete machining and assembly with internal components.

Note: This engine block is designed for racing and high-performance applications. Not legal for use on emissions-controlled vehicles or public roadways.