Edelbrock RHS LS Aluminum Race Block (Part Number 54903U) — Ready to Hone, 9.250-Inch Standard Deck, 4.120-Inch Bore

Block Specifications: Designed from heavy-duty A357-T6 aluminum material; 4.125”-4.165” siamese cast bore walls w/ press-in spun cast iron liner; Available in standard (9.240”) & tall (9.750”) deck heights w/ beefy .750” deck thickness; Both standard deck (5.67”/5.87”- same as LS7) & tall deck (5.94”/6.38”) cylinder liner lengths available; “Long arm friendly” – Accommodations for up to 4.6” stroke w/ standard rod pin diameters (2.100”) & oversized 60mm camshaft; Main cap surface area maximized at mating surface & large fillets from cap to cross bolts for added strength; Designed for clearance – side oil galley moved outboard & engineered rod clearance come standard; Significantly increased windage passage area under bores & around caps over LS7/LSX engines; 6 head bolt design w/ full water jacket around the cylinders (based on LS7 design); Bay-to-bay breathing improved w/ increased side window area versus LSX & LS7; Extra-large windows in valley for access to inboard “6th” head bolt; Extra-long liners for standard (5.87”) & tall (6.38”) decks RHS LS Block, Standard 9.240" Deck, .842 Lifter, 50mm Cam Bearing - Hone to 4.120" Bored and Ready To Hone.

• P1 MFG main stud kit standard with enough material in castings to accommodate up to a 0.5 inch fastener
• Gen III/Gen IV compliant with race mounts for Gen I, Gen II, Gen III & Gen IV engines
• Rolled threads on all threaded holes for added strength
• Chilled main bearing bulkheads for added strength
• Optimized billet main caps & improved windage

The Edelbrock RHS LS Aluminum Race Block (Part Number 54903U) is engineered for high-performance automotive applications, combining durability with advanced design features. Constructed from heavy-duty A357-T6 aluminum, this block offers a robust foundation for racing engines. It features a 4.125-inch to 4.165-inch siamese cast bore walls with a press-in spun cast iron liner, providing excellent durability and heat resistance. Available in standard (9.240 inches) and tall (9.750 inches) deck heights, the block accommodates a variety of engine configurations and stroke lengths up to 4.6 inches, making it highly versatile for custom builds. Both standard deck (5.67 to 5.87 inches) and tall deck (5.94 to 6.38 inches) cylinder liner lengths are available, allowing precise tailoring to your performance needs. The design includes a full water jacket around the cylinders with a six-head bolt pattern, inspired by LS7 architecture, ensuring optimal cooling and structural integrity. Enhanced side oil galley positioning and increased windage passage areas improve oil flow and reduce drag, contributing to engine longevity and efficiency. The large valley windows provide easier access to the inboard sixth head bolt, facilitating assembly and maintenance. Extra-long liners for both standard and tall decks ensure precise fitment, and the block is ready for honing, saving valuable setup time. Features such as rolled threads on all threaded holes, chilled main bearing bulkheads, and optimized billet main caps bolster strength and durability, meeting the demands of high-horsepower applications. The block is compatible with Gen III/IV race mounts and includes provisions for up to a 0.5-inch fastener in the main studs, making it suitable for a wide range of racing builds. Please note, this product requires acknowledgment of non-CARB compliance and is not CARB approved. The Edelbrock RHS LS Aluminum Race Block is ideal for enthusiasts seeking a high-quality, reliable foundation for their custom high-performance engine projects.

Features:

• Heavy-duty A357-T6 aluminum construction for durability

• Siamese cast bore walls with press-in spun cast iron liner

• Available in standard (9.240") and tall (9.750") deck heights

• Beefy .750" deck thickness for strength

• Compatible with standard and tall deck cylinder liners

• Designed for up to 4.6" stroke with standard rod pin diameters

• Maximized main cap surface area and large fillets for added strength

• Optimized clearance with side oil galley repositioning and engineered rod clearance

• Increased windage passage area for improved oil flow

• Six-head bolt design with full water jacket based on LS7 architecture

• Enhanced side window area for bay-to-bay breathing and access to sixth head bolt

• Extra-long liners for both standard and tall decks

• Ready to hone, saving setup time

• Includes rolled threads, chilled main bearing bulkheads, and optimized billet main caps

Air Freight Prohibited: false
Not Carb Approved: true
Carb Acknowledgement Required: true
Ltl Freight Required: false
Prop 65: Y
Part Type: automotive
Epa: N/A
Regular Stock: false
Units Per Sku: 1