In the world of racing and performance, BIGGER is always better. Ford Performance gets it - and that's why it offers BOSS small blocks in Big Bore versions. The Ford Performance BOSS blocks are designed to be a replacement for the legendary BOSS 302 and BOSS 351 blocks using the latest technology and manufacturing techniques available. Cast from diesel grade iron with siamese bores, thick cylinder walls and decks, BOSS block strength is far superior to any Ford production block ever offered. Ford Performance Big Bore version of the BOSS 302 block makes it simpler and more economical to build really BIG small blocks. To insure the most precise bore location, concentricity and integrity, the BOSS Big Bore blocks are machined an additional .125" during the initial block fixturing and boring stage. With an unfinished bore size of 4.120", Ford Performance BOSS 302 Big Bore blocks will support engine sizes up to 363 cubic inches. The Ford Performance BOSS block capability has been proven around the world, both on the track and on the street. And, all Ford Performance BOSS blocks are cast and machined to the highest industry standards in the USA. Requires special length 1/2" head bolts M-6065-BOSS or head studs M-6014-BOSS recommended with M-6049-X306/307/Z304DA heads; Uses common OD cam bearings M-6261-J351/R351; Unique cam plug M-6026-S351 included; M-6051-S331 or M-6051-CP331 head gasket recommended; Designed to be compatible with the original 302 and 351W blocks. Designed to use stock type timing cover, timing Cover M-6059-D351 recommended ; Fits factory Mustang oil pan with custom oil pick-up tube M-6622-BOSS302; Retains clutch cross shaft pivot hole; Original Style oil filter location; Original motor mount boss locations; Original bell housing pattern; Weighs approximately 163 lbs.; The foundation for 8.2" deck projects