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Ford Stock-Block Stroker Engine Swap Part 1We Build A 331CI Small-Block Ford, And You Can Do It, Too. From the May, 2009 issue of Muscle Mustangs & Fast Fords By Steve Baur Photography by Competition Products, Jason Combs, Steve Baur
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Dig in and prepare to get your hands dirty. It's time to add some cubic inches to your 5.0L Mustang, and it just might be easier than you think. With the average EFI 5.0L Mustang now some 20 years old, it's going to be time for a rebuild. For a few bucks more, you can add more cubes, more horsepower, and more torque. A few issues back, we brought you a budget rebuild story called the "Recession Special." Adding new crank and rod bearings, along with new piston rings can freshen a tired 5.0L and give you a few more years of life from the tough-as-nails small-block Ford. This month, we're here to show you that you can employ those same techniques from the budget build and add a stroker rotating assembly at the same time. Competition Products supplied... Competition Products supplied our rotating assembly. It's competitively priced at $1,089.95 (PN SS331FF) and includes a cast steel crank, 4340 steel rods with ARP cap screws, flat-top HRC forged pistons, connecting rod and main bearings, and file-fit plasma moly rings. For an extra $200, we had Competition Products balance the assembly. We started with a seasoned 5.0L stock block and dropped it off at H&M Parts Warehouse in Jacksonville, Florida, where the crew bored the cylinders 0.030-inch over, performed a finish hone, and installed new cam bearings, freeze plugs, and oil-galley plugs--not bad for just a little over 200 bucks. Most stroker assemblies utilize custom pistons that move the wristpin higher in the piston to allow for the longer connecting rod, and since they're already making a new piston to allow for more cubic inches, it just makes sense to maximize the piston to do the same. That being the case, the pistons are made for a 4.030-inch bore size. We also had the machine shop hot-tank the block before they gave it back to us. For our rotating assembly, we turned to Competition Products of Oshkosh, Wisconsin. Since 1970, the company has supplied engine builders and enthusiasts alike with great deals on everything from engine parts to oil. If it's under the hood or beneath the chassis, chances are Competition Products has something to replace it or make it better. After placing our order, we had the rotating assembly sitting at our doorstep in just three days. It might be quicker if you live closer, as it ships the same day the order is placed. The piston-ring end gap was... The piston-ring end gap was filed to fit the cylinders according to SRP's instructions. The top ring was filed for a 0.022-inch gap and the bottom ring for a 0.028-inch gap. The engine will be shoehorned between the fenders of a Fox-body coupe Mustang, so we opted for the 331ci stroker rotating assembly as opposed to the 347ci option. It's a light car, and we'd rather forfeit the extra torque of the 347 for the better rod ratio the 331 offers. There's only $10 difference between the two kits. The basis of the 331ci combo is a cast steel crankshaft with a 3.250-inch stroke on the rod journals. Said journals swing 5.4-inch Scat I-beam connecting rods that have been fitted with ARP fasteners. Finally, an octet of SRP forged flat-top aluminum pistons will fill the cylinders and get the crank and rods moving. Competition Products also includes HRC plasma moly file-fit piston rings and balanced the entire rotating assembly for us. The company also provided us with a Professional Products harmonic balancer for the stroker's 28-ounce imbalance, as well as an SFI flexplate to match our Mustang's C4 automatic transmission. The HRC piston rings were... The HRC piston rings were filed and the end gap checked within the cylinder bore. Topping off our stroked and poked short-block is a set of Trick Flow Specialties all-new Fast as Cast 190cc Twisted Wedge cylinder heads. TFS heads have always been relatively affordable, and in this day of CNC this and that, the company opted to give its consumers a CNC-sized port in a cast head for a cast price. Going off of its popular CNC-ported 185cc runner Twisted Wedge head, TFS used the port designs to produce a 190cc intake runner and 66cc exhaust runners. These 190cc runner heads retail for $1449.95, compared to the CNC-ported 185cc castings that sell for $1799.95. "Our competitors have everyone believing that you need a CNC head to make power," says Trick Flow tech Greg Changet. "Some people will want a CNC head no matter what you tell them, but with the Fast as Cast head, you get the big runner without the big price." And you get the flow numbers, too. We'd like to see what a quick cleanup job could do with these heads, and we may get to that in a future article.  We installed the crank bearings,...  We installed the crank bearings, coated them with assembly lube, and set the crankshaft into position. The main caps were torqued, and assembly lube was applied to the rod journals.  The cast-steeL crankshaft...  The cast-steeL crankshaft included in the Competition Products stroker assembly was chosen for its durability in a street and strip environment. It'll still be in one piece long after we split the block, if we get that far in power production.  The connecting rods in the...  The connecting rods in the Competition Products assembly are 4340 forged-steel, I-beam pieces from Scat. They're fitted with ARP cap screws and thankfully cleared our stock-block so we didn't have to perform any of the normal grinding commonly associated with small-block Ford stroker engines.  With all of the piston rings...  With all of the piston rings filed for a perfect fit, the pistons were fitted to the rods and installed in the block. SRP provides plenty of instructions with the pistons to make sure you have the piston rings clocked correctly.  We took a photo of another...  We took a photo of another stroker engine build to show you where you'd need to clearance the block if you encountered interference with the rotating assembly. This engine utilized the same 3.25-inch stroke and 5.4-inch long connecting rod as our build, but it used an H-beam-style rod, which has more meat on the big end of the rod. The extra metal moves the cap screw location towards the end, which is where the block interference occurs.  To let this 331ci small-block...  To let this 331ci small-block breathe, we called up Trick Flow Specialties and ordered a set of its brand-new Fast as Cast 190cc Twisted Wedge cylinder heads. Part number TFS-51400015 nets you aluminum Twisted Wedge heads that feature 2.020-inch intake valves and 1.60-inch exhaust valves. Trick Flow used its CNC-ported 185cc runner port design and cast it into a new head. That way you get the flow of the ported head at a cast price. The 190cc heads utilize a 7/16-inch rocker stud size, as well as 5/16-inch pushrods. The Fast As Cast cylinder... The Fast As Cast cylinder heads offer up a 190cc intake runner volume, while the exhaust measures 66 cc. Rounding out the induction side of the 331 is TFS' 5.0L R manifold, a BBK 75mm throttle body, and a TFS Trackmax Stage 2 camshaft to move the air in and out. Best of all is that you can order all of the parts from just two places, and with the same-day shipping from Competition Products and Summit Racing Equipment, you can have the combination built and shoehorned into your street machine in no time at all. This month, we're bringing you the buildup of the engine; then we'll follow up with an engine dyno test, a chassis dyno test, and conclude with a quarter-mile drag test. You'll get to see what the parasitic loss is from crank to wheel horsepower, as well as how this stock-block stroke swap performs in a Fox-body Mustang at the track. The combustion chamber volume... The combustion chamber volume is still the standard Twisted Wedge 64cc, though the heart-shaped chamber does receive a CNC cut that is said to improve mid-lift numbers. Cylinder-Head Flow Numbers
Tested on a 4.030-inch bore. Flowed at 28 inches on a Superflow SF-600Lift | Lift | Intake | Exhaust | | 0.100 | 71 | 57 | | 0.200 | 145 | 115 | | 0.300 | 214 | 150 | | 0.400 | 257 | 187 | | 0.500 | 268 | 194 | | 0.600 | 273 | 197 |
 The brain of our stroker engine...  The brain of our stroker engine revolves around a Trick Flow Trackmax Stage 2 hydraulic roller camshaft (PN TFS-51402001) and billet-steel timing chain and gears (TFS-51478520). Trickflow also provided us with a couple sets of pushrods to choose from after we confirmed the correct size using their pushrod length checker (TFS-9000). We ended up using a 6.700-inch pushrod (PN TFS-21406700).  While we could've gone with...  While we could've gone with the Trick Flow Track Heat-intake manifold, we opted for the higher RPM R-series after talking with Trick Flow. Part number TFS-51500003 is the silver powdercoated R manifold for the 5.0L Mustang with a 75mm throttle-body opening. You can also get the R manifold with a 90mm opening, in black or natural aluminum finishes. There's no provision for EGR. Topping off the cylinder heads are Trick Flow's silver valve covers (PN TFS 51400801).  Finishing off our stroker...  Finishing off our stroker buildup are these components from Competition Products. A Melling standard volume oil pump (PN M68), a PRW SFI 157-tooth flexplate (PN PRW1830204), and a Professional Products SFI 28-ounce harmonic damper with pulley spacer (PN PP90006, PP81007). Not shown is our 75mm throttle body from Brothers Performance.  The Trick Flow Trackmax Stage...  The Trick Flow Trackmax Stage 2 hydraulic roller camshaft features a split duration of 224/232 at 0.050, along with a split valve lift of 0.542 inch on the intake and 0.563 inch on the exhaust when using a 1.6:1 rocker arm. Lobe separation is 112 degrees. We installed the cam straight up.  Making sure the timing events...  Making sure the timing events happen when they're supposed to is a Trick Flow billet-steel timing set (PN TFS-51478520). This is a heavy-duty piece that has a three-position key way for running the camshaft straight up, or 4 degrees advanced or retarded.  Making sure our stroker engine...  Making sure our stroker engine maintains a fresh supply of clean oil is this Milodon 7-quart oil pan (PN 31125). It's designed for extreme street or strip applications and features oil-control baffles to subdue any unwanted oil movement. This keeps the oil supply right with the oil pickup tube where it needs to be. The pickup (PN 18380) can be used with Milodon's optional windage tray for even greater power gains.  Make sure you have the oil-pump...  Make sure you have the oil-pump shaft properly seated in the oil pump and block before tightening the oil pump itself. It doesn't hurt to upgrade to a high-performance shaft at this time either, but a stock one will work. With the oil pump and pickup... With the oil pump and pickup mounted, you'll need to check the pickup-to-pan clearance. Ideally, you want about a half-inch of space between the two. We used a suitably sized nut to simulate the desired distance and then put the pan on. If it hits, pull the pan off and tweak the pickup and check again. Do this until the nut no longer hits the pan.  The Milodon pan can be used...  The Milodon pan can be used with or without the factory support rails. It also features a leak-free screw in oil dipstick bung to work with Milodon's stainless steel dipstick, and offers front and rear sumps just like your stock pan.  With the Professional Products...  With the Professional Products SFI damper installed, we set the engine to top dead center on the No. 1 piston.  When installing cylinder heads,...  When installing cylinder heads, the locating dowels are always an issue. Trick Flow now offers its own (PN TFS-51400420), and the beefy continuous tube design will keep your cylinder heads properly located and prevent them from moving around on the deck far better than the thin stock pieces. They're sold in sets of four.  Using a Trick Flow engine...  Using a Trick Flow engine gasket kit (PN TFS-5140E913), we installed the cylinder heads. ARP head bolts were used in this build, though Trick Flow recommends using ARP studs. The bolts were torqued in increments of 55, 65, and 70 lb-ft.  We installed the Trick Flow...  We installed the Trick Flow 6.700-inch pushrods and aluminum rocker arms (PN TFS-51400520). The rocker arms feature a 1.6:1 ratio and are 7/16-inch stud-mount units. We rotated the engine over and as the exhaust valve opens, we adjust the intake rocker. As the intake valve closes, we adjust the exhaust valve. The rockers were set at zero lash, followed by one-half turn of the nut.  Finished for now, our little...  Finished for now, our little stroker that could is slated for the engine dyno next. We'll follow that performance with chassis dyno and track numbers in an upcoming issue.  Using the pushrod length checker...  Using the pushrod length checker will give you a measurement, and while you can eyeball the rocker tip placement on the valve, it's a good idea to turn the motor over and verify how the rocker is working the valve tip. We slipped a piece of paper between the valve tip and rocker and turned the engine over a few rotations. Here, you can make out the circle of the valve tip and note that the rocker is riding right in the center of the circle. This is optimal. If the paper gets cut anywhere around the edge of the circle, or if the roller tip line is not in the center, then you may need a different length pushrod.  The lower intake manifold...  The lower intake manifold is next. Trick Flow says the 190cc heads should use a Fel-Pro 1262 intake gasket, but we found the 1250 to be a better fit. Make sure you torque the lower manifold in the sequence stated by the Trick Flow instruction sheet, and that you do not exceed 22 lb-ft of torque on the bolts. Going over that can lead to cylinder-head distortion.
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