Richard Holdener
July 5, 2013

5.0L Performance packages-347 Stroker

Engine Specs-Modified 347 (EFI)
Displacement 347 ci
Bore 4.03
Stroke 3.40
Pistons Stock flat-top JE
Forged Yes
Compression 10.5:1
Rods SCAT 5.40-inch H-beam
Forged Yes
Heads Procomp Electronics 210cc CNC
Aluminum Yes
Iron No
Ported Yes
Intake Valve 2.055-inch
Exhaust Valve 1.60-inch
Chamber Size 62cc
Upper Intake Edelbrock Performer RPM II
Ported No
Lower Intake Edelbrock Performer RPM II
Ported No
Throttle Body 75 mm Accufab
Injector Size 36-lb/hr
Fuel System Aeromotive
EFI System Holley Dominator
MAF Stock Ford (not used on engine dyno)
Custom Chip No
Distributor Stock (MSD used on dyno)
Header (style) Hooker Super Comp long-tube
Header Size 13⁄4-inch
Cam Crane hyd-roller (hyd/solid-roller)
Intake Lift 0.563
Exhaust Lift 0.584
Int Dur Degrees 232 @ 0.050
Ex Dur Degrees 240 @ 0.050
LSA 112
Rockers Crane Gold roller
Ratio 1.6:1
Exhaust 2.5-inch with Borla mufflers
Max Power Output (dyno) 462 hp @ 6,200 rpm
Max Torque Output (dyno) 434 lb-ft @ 4,500 rpm

5.0L-Stock vs. Modified 347 EFI

Since the power output of any combination is a function of the major components and the displacement, an easy way to improve power without resorting to decreased driveability is to add cubes. Remember, there really is no replacement, especially when it fits conveniently in the same physical package as the stock 302. The 347 is a common stoker assembly, and our test components were supplied by Scat and JE pistons. Forged components ensured plenty of strength, since we later ran both boost and nitrous on these 347 combinations. The injected version was equipped with a set of CNC-ported heads from Procomp Electronics, a healthy Crane hydraulic-roller cam (0.563/0.584 lift, 232/240 duration, and 112-degree LSA), and Edelbrock Performer RPM II upper and lower intake. Also present were a set of Hooker Super Comp headers, complete Aeromotive fuel system feeding 36-pound injectors and an Accufab 75mm throttle body. Thanks to tuning from the Holley management system, the injected 347 combination produced 462 hp at 6,200 rpm and 435 lb-ft of torque at 4,500 rpm.

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Engine Specs-Modified 347 (Carb)
Displacement 347 ci
Bore 4.03
Stroke 3.40
Pistons JE flat-top
Forged Yes
Compression 10.1:1
Rods Scat 5.4 H-beam
Forged Yes
Heads TFS Twisted Wedge 185 CNC
Aluminum Yes
Iron No
Ported Yes
Intake Valve 2.02 inches
Exhaust Valve 1.60 inch
Chamber Size 64 cc
Intake Edelbrock Performer RPM Air Gap
Carburetor Holley 950 HP
Spacer No
Fuel System Aeromotive
Distributor Stock (MSD used on dyno)
Header (style) Hooker Super Comp long-tube
Header Size 13⁄4-inch
Cam TFS Stage 3 hyd-roller (hyd/solid-roller)
Intake Lift 0.579
Exhaust Lift 0.595
Int Dur Degrees 236 @ 0.050
Ex Dur Degrees 248 @ 0.050
LSA 110
Rockers Crane Gold roller
Ratio 1.6:1
Exhaust 2.5-inch with Borla mufflers
Max Power Output (dyno) 482 hp @ 6,600 rpm
Max Torque Output (dyno) 442 lb-ft @ 4,900 rpm

5.0L Stock vs. Modified 347 Carb

Once again we employed a 347 stroker assembly, but this one came in the form of a Dart SHP stroker assembly. The SHP motor combined a 4.03-inch bore with a 3.40-inch stroke. The flat-top (Mahle) pistons were combined with a TFS Stage 3 hydraulic-roller cam that offered a 0.574/0.595-lift split, a 236/248-duration split (at 0.050), and a 110-degree lobe-separation angle. The combination was also topped off with a set of CNC-ported Twisted Wedge CNC 185 cylinder heads from Trick Flow Specialties. Topping the combination was an Edelbrock Performer RPM Air Gap intake and 750 HP Holley carburetor. As with the 302 combinations, the carbureted 347 combo produced slightly more peak power than the EFI version, but slightly less peak torque. This carbureted stroker produced 482 hp at 6,600 rpm and 424 lb-ft at 4,900 rpm. Approaching 500 hp, this 347 is a healthy street motor but one with a nice, broad torque curve.

20. Run on the dyno with a Box R upper and lower intake and 90mm Accufab throttle body, this normally aspirated 363 produced 519 hp at 6,600 rpm and 469 lb-ft of torque at 5,000 rpm. Eventually, this motor would see over 1,000 hp in turbocharged form.