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.
- 4.125" bore capacity, finished at 4.115" rough bore. Also available in standard bore version, part number: M-6010-BOSS302
- 8.2" deck height, finished at 8.200" plus .010" to .015"
- Designed with optimized cylinder wall length for stroker applications up to 3.5" with no grinding or clearancing. (Depends on crank/rod manufacturer)
- Splayed 4-bolt main on 2, 3, 4, main caps
- 2-bolt main on first and fifth main caps
- Main bearing bores finished to low limit
- Finished lifter bores
- Machined to accept factory roller lifter guides and lifter guide retainer
- Fits factory 1979 - 1995 Mustang oil pan with custom oil pickup tube, part number: M-6622-BOSS302
- NASCAR inspired front oil feed on both lifter galleys.
- Revised cooling system passageways
- Siamese bore
- Increased bulkhead material
- Threaded core and galley plugs (straight thread port plugs with O-ring)
- Requires special length 1/2" head bolts M-6065-BOSS or head studs M-6014-BOSS recommended with M-6049-X306/307/Z304DA heads
- Designed for M-6049-X306//X307/C3/D3/Z304DA cylinder heads. Not designed for production 302/351W or M-6049-Y302/Y303/X302/X303/X304/X305 cylinder 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 and includes the following features:
- Designed to use stock type timing cover, timing Cover M-6059-D351 recommended (includes fuel pump provision)
- 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.
- Great price and value
- The foundation for 8.2" deck projects
Proven performance - used in Ford Performance sealed 347cid race engines and Ford Performance high performance crate engines, a proven winner out of the crate and thousands of laps before rebuild.
Ford Performance BOSS Blocks