World Products has completely redesigned and re-tooled the famed Merlin Big Block to achieve new heights in performance and ease of use for engine builders and racers. Starting with all new foundry tooling and machining fixtures, World has made improvements to virtually every area of the new Merlin IV with the goal of producing the most technologically advanced and best performing iron BBC block available today!
New features include thicker main webs for increased strength and thicker cylinder walls which are nominally .310-inch @ 4.600-inch bore. In addition to the standard BBC 9.800-inch and 10.200-inch deck heights, new are deck heights measuring 9.500-inch, 9.850-inch and 10.250-inch. These allow greater versatility for specific engine combinations. Head bolt holes are blind on all available deck heights and deck thickness is nominally .600-inch.
The Merlin IV is available with a 2.120-inch journal for standard BBC cam and standard .842″ lifter bores, or with a 2.283-inch journal for a 55mm Babbitt cam and .904-inch lifter bores. Cam journals up to 2.480-inch or 60mm Babbitt and 1.060-inch lifter bores can be accommodated, but are not stocked by World Products. World also has increased the volume in the priority main oiling system and added a front oil feed for dry sump systems, and relocated the lifter oil feeds and restrictor provisions to the front of the block.
The new block features siamese cylinder bores in 4.245-inch, 4.495-inch or 4.595-inch which finish at 4.250-inch, 4.500-inch and 4.600-inch respectively. Water jackets have been further enlarged for better cooling capacity. Nodular iron or 1045 billet steel 4-bolt main caps are standard and feature dual register to prevent cap walk. High strength 1/2-inch ARP fasteners are employed to secure the main caps, with bolts used on the nodular caps and studs for the billet caps.
Cast and machined in ISO 9000 certified facilities, the Merlin IV is 100% American made and subject to stringent quality assurance procedures to ensure superior quality and performance. This new block is sure be a favorite among racers and professional engine builders.
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