As always, the 347 stroker was given a thorough break in prior to running in anger. Jetting the Holley carburetor was made easier with the Percy’s external Adjust-a-Jet system. After timing sweeps indicated that the optimum timing was 35 degrees, we were rewarded with peak numbers of 482 hp at 6,600 rpm and 424 lb-ft of torque at 4,900 rpm. The extra displacement, cam, and compression illustrated their worth by offering a broad torque curve, bettering 400 lb-ft from 4,800 rpm to 6,100 rpm. This compares to 376 hp and 355 lb-ft of torque from the 5.0L tested previously. The original TFS-headed 5.0L managed to exceed 333 lb-ft of torque from 4,000 to 5,900 rpm, but neither the peak nor average torque production could compare to the stroker combination. Though we still had yet to max out the capacity of the 185cc Street Port Twisted Wedge Heads, this test clearly illustrated that when it comes to performance, sometimes bigger really is better.
8 To improve the rod-to-stroke...
8 To improve the rod-to-stroke ratio, the 3.40-inch forged steel crank was combined with a set of 5.40-inch forged steel connecting rods.
9 The final component included...
9 The final component included forged flat-top pistons from Probe Racing. Note the dual valve reliefs indicating that this piston would accept either TFS Twisted Wedge or inline valve heads.
10 Working with the increased...
10 Working with the increased displacement was a camshaft upgrade. Comp Cams came through with an XFI236HR-14 hydraulic roller profile designed specifically for stroker applications that offered 0.579 lift, a 236/248-duration split and a 114-degree LSA.
11 The late-model hydraulic...
11 The late-model hydraulic roller block readily accepted the factory hydraulic-roller lifters (from Comp) and spyder retaining hardware.
12 After assembly of the...
12 After assembly of the short block, we installed a complete Milodon oiling system including a pan, pick-up, and windage tray. The Milodon oiling system improved both power and reliability.
13 The Track Heat engine...
13 The Track Heat engine kit included a set of aluminum, 1.6-ratio roller rockers. The rockers were removed from the 302 and reused along with the timing chain and hardened pushrods.
14 Originally, we hoped to...
14 Originally, we hoped to run the 347 in injected form, but were forced to choose carburetion instead. We ran both an Edelbrock RPM Air gap and Victor Jr. on the 347, but the Air Gap offered equaled the peak power and offered significantly more average power than the Victor Jr.
16 Run on the engine dyno...
16 Run on the engine dyno with a set of Hooker headers, Meziere electric water pump and MSD ignition, the carbureted 347 produced peak numbers of 482 hp and 424 lb-ft of torque. The TFS-headed 347 offered nearly 100 more horsepower than the 302, but there was considerably more flow to be had. We know there is still another 100 hp or so waiting to be unleashed in these impressive cylinder heads.
15 Carb chores on the dyno...
15 Carb chores on the dyno were handled by a Holley 750 HP carburetor. Jet changes to the Holley could be performed externally thanks to a Percy's Adjust-a-Jet system.
Here is what happens when you add cubes, cam, and compression to a 5.0L Ford. Modified by the Track Heat engine kit from Trick Flow Specialties, the high-mileage 5.0L Ford produced 376 hp and 355 lb-ft of torque. Using the same Street Port heads, the carbureted 347 produced 482 hp and 424 lb-ft of torque. Thanks to increased displacement, compression, and wilder cam timing, the 347 offered more power everywhere.