There can be only one original. The Boss 302 was a two-year (1969-70) production pushrod motor that thrilled Ford fans everywhere and often bested the competition. The Boss was a truly formidable powerplant-but that was 35-plus years ago. What about today? In the age of modular motors there is no denying their performance, but there are still plenty of hot rodders who would like to enjoy the power that can come from a truly potent small-block V-8. When Ford Racing Performance Parts announced it would bring back the Boss 302, Ford aficionados everywhere were (are) thrilled.
Let us start with a horsepower primer on the original Boss 302 versus the new Boss. The original Boss 302 came out of Detroit with 290 hp at 5,800 rpm but could be enhanced with Ford factory hi-po parts such as low-restriction air cleaner (C5ZZ-9600-W); add a larger four barrel (C8AZ-9510-AD) and a high rise aluminum intake (C9OZ-9424-D) and an additional 31hp showed up; an enhanced hydraulic camshaft (C9OZ-6250-C) added an additional 40 pones; dual point distributor (C5OZ-12127-E); cylinder heads (C9OZ-6049-F) equipped with larger exhaust valves (C9OZ-6505-A) and intake valves (C9OZ-6507) provided another 32 hp; pop-up pistons took advantage of the improved heads by using part numbers C9OZ-6109-B (left) and C9OZ-6108-AA (right) added to a set of enhanced connecting rods (C6AZ-6200-C). There was a mechanical cam (C7FE-6250-A) for the truly serious performance enthusiast adding another 59 hp at 6,000 rpm.
Enough of the old, what about the new? Let's start with the new Boss 302 block and see what enhancements have been made by Ford to improve on a proven package. For the record, the part number on the new Boss block is M-6010-BOSS302. The 165-lb block (old Boss was 143 lb) is made from diesel grade heat-treated cast iron (one-piece main seal) as compared to the original (two-piece main seal) and cast iron. (Approximate weights for a modern Boss 302 are 543 lb while a long-block is 425 lb.)
Both blocks come with four-bolt mains (cylinders two, three, four; and two-bolt on first and fifth main caps), while the new block features engineered cross-drilling Siamese bores. The new Boss caps are made from nodular iron and are machined and splayed. The new block utilizes O-ring sealed and straight thread freeze plugs and oil galley plugs while the old bock utilized screw-in tapered pipe thread on the freeze plugs and straight pipe thread on the oil galley plugs. The head bolts on the old Boss are 7/16 inch while the new are 1/2 inch. Coupled to this are the main bolts at 7/16 inch on inner (1-5), and 3/8 inch on outer (2, 3, 4) for the old Boss, while the new Boss employees 1/2 inch inner (1-5), and 3/8 inch outer (2, 3, 4). For those who wish to squeeze out additional cubes, the old block had a recommended maximum bore size of 4.030 inches for a total of 347 cubes. The new Boss has a recommended max bore size of 4.125 inches and max stroke is 3.400 inches for 363 cubes. In its 302-inch configuration, the stroke is based on a 3.00-inch cast crank while the 347 version comes with a 3.40-inch forged crank.