Jim Smart
January 1, 2013

Imagine the convenience of an off-the-shelf crate engine displacing 427ci that you can assemble and install in your Mustang over a weekend. On the outside, it looks like a 351W small-block. Inside, it displaces big-block cubes ready to make axle-twisting big-block power.

We caught up with Scott Drake Enterprises’ Jerry Choate and his wife, Carlyn, as they were building a ’65 Mustang fastback in their Las Vegas shop. The power objective was a civil yet aggressive 351W-based stroker, something that would come on strong at wide-open throttle, yet be passive enough for a road trip with a five-speed manual and compromise cogs in back. Jerry knew from experience that you can overbuild to the point where the Mustang becomes a chore to drive.

Jerry chose Ford Racing’s new BOSS short-block, M-6009-427F, displacing 427ci for a small-block that thinks it’s a big-block. Ford Racing begins with the M-6010-BOSS35195 block with four-bolt mains and 9.500-inch deck height, then fills the bulletproof short-block with a Scat 4340 4.000-inch steel crankshaft with 4340 H-Beam 6.200-inch connecting rods and Mahle 4.125-inch forged pistons with valve reliefs for Z304, N351, GT-40 or other inline valve Windsor cylinder heads. It’s compatible with hydraulic roller tappets and comes completely assembled for under $5,000.

Although the short-block arrives as a ready-to-complete assembly, there are items you need to check when you get it on an engine stand, including crankshaft endplay, connecting rod side clearances, rear main seal (should have assembly lube on lip), piston deck height, cam bearing condition, block plugs (are they tight?) and cooling passages and oil galleries to make sure they are clear. These checks should be performed on any engine you receive, whether it’s a crate engine or a custom build from a local shop. It is easier to check these things now then have to pull the engine later on because you missed something.

The beauty of the M-6009-427F short-block is that you can go in any direction with heads, induction, and cam. Because this is a high-performance short-block with 4.125-inch forged pistons, 4.000-inch stroke, H-beam rods, and steel crank, it is for high-rev activity, meaning you can commute Monday through Friday and go racing Saturday night depending on what you do with cam and induction.

You have a choice when it comes to cylinder heads for the BOSS M-6010-BOSS35195 block. We decided to go with one of the two Ford Racing street/race heads for the BOSS block—M-6049-X306 with 64cc chambers. There is also the M-6049-X307 casting with 58cc chambers. Choice depends on how much compression you want. Ford Racing’s Jesse Kershaw recommended the 64cc chamber to keep compression safe for pump gas. These are basically GT-40 Turbo Swirl heads with nice revisions like beehive valve springs, 1.94/1.54-inch valves, and tight wedge chambers with plenty of quench. Ford Racing tells us these are easily 65 bolt-on horsepower. Of course, your results will vary depending upon cam selection and building technique.

Choate delivered the X306 heads to Steve Baker at Baker Cylinder Heads for minor prep work to help improve airflow and get rocker arm geometry where we wanted it. For camshaft, Choate decided to go with an off-the-shelf Extreme Energy roller hydraulic camshaft (part number 35-427-8) from Comp Cams with link bar hydraulic roller tappets and one-piece, thick wall pushrods. On top, he mounted Harland Sharp 1.6:1 roller rocker arms on ARP 7⁄16-inch studs.

With a Holley 750-cfm four-barrel carburetor and Edelbrock Performance intake, Choate believes this 427W will make in excess of 500 horsepower and roughly 550 lb-ft of torque.

Photo Gallery

View Photo Gallery
27. When we contacted Jim Hairston at JBA Headers, he turned us onto the #1653S mid-length header for 351W in a ’65-’66 Mustang, which is a tight fit but perfect for this header combo. The #1653S header is made from ceramic-coated stainless steel with a ball and socket collector design, which means no collector gaskets to fail. This is a nice compromise between a shorty and a long-tube header.