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Ford Mustang 4.6 Stroker Kit - Adding Cubes To Cammer Part 1
Yes, You Can Build A Modular Stroker Engine. Follow Along As The Good Folks At SHM Show You How.
It doesn't take long to realize that the pushrod 5-liter engine is still the main focus of the late-model Mustang craze, with the list of stroker combinations long enough to make up a small novel. However it has been six model years since the Mustang received one in its engine bay on an assembly line.
The modular family of engines has replaced them and have received both praise and bombings from the critics. The 4.6 and 5.4 engines are still a far cry from the level of simplicity and interchangeability of the old small-block Fords, but one must remember that it took almost 20 years for the those to mature into the optimized configuration that they have reached.
Sean Hyland and his team of engine builders, tuners and technicians are quickly gaining ground on the years of advancement advantage that the Windsors have by dedicating themselves to the development of the modular motor family. Their efforts started from the very beginning of 1995 with the inclusion of the 4.6, 5.4 and 6.8 engines, both in performance and durability. They have excelled in the drag racing arenas with cars such as John Mihovetz's 7-second supercharged Stang and Joe Hutchins' mid-10 second normally-aspirated Mustang. John Buscema also topped 205 mph in the Silver State Challenge with one of Sean's 4.6 4V powerplants in his Cobra.
SHM is a self-proficient facility with an in-house machine shop and head porting department, complete with a flow bench and an engine dyno as tools to aid in their cutting edge research and development. The Canadian outfit also offers turnkey packages from its qualified installation technicians, who optimize your project on the chassis dyno before it's stamped with the SHM seal of approval.
Now Sean Hyland & Co. is happy to introduce the production of the first group of stroker motor kit options for your 4.6 Mustang. There will be three basic kits, the 5.0-, 5.2- and 5.4-liter, all available with a long list of options to upgrade your project to the performance level you desire, or for most of us, that our pocketbook can afford.
Each kit is designed for the '96-98 Cobra engine, which like all Cobra engines were aluminum. The tremendous performance advantages of the 4V motor made it a perfect candidate for a stroker motor kit. The factory may not have taken advantage of the technical benefits but the aftermarket certainly has, as we will point out along the way.
The 5.0 stroker crank kit is the only one available as an installation kit, and what that means is that no special machining is required except a standard .020 overbore on the engine block to assure your new 5.0 gets a fresh start. It includes the forged stroker crankshaft, piston and rod assemblies and the bearings and gaskets.
Both the 5.2 & 5.4 stroker crank kits will require SHM's installation of special sleeves in the block to accommodate the larger pistons required to achieve the additional displacement. Just think of the monster torque one could add to the 4.6s' high winding capabilities with more cubes.
Now rather than just show the components, we decided to let the pros at SHM show how they would assemble a complete long-block assembly.
This presented us with a great opportunity to check out what makes one of these new modular type engines tick, from the inside out. Most readers have probably gone through what seems like a hundred Windsor engines, but few have had the chance to walk step by step through the assembly process of the new modular stuff.
Sean's ace engine builder, John Mummery, let us ride shotgun to document the engine building process of one of its 5.2-liter stroker motors (that's 318 cubic inches for you old-timers). "First of all, each block we machine is carefully blueprinted and documented for specific piston-to-bore, crankshaft, connecting rod and main bearing clearances." stated modular motor guru and proprietor Sean Hyland.
After the block comes back from its boil, bore, hone and decking treatment, make sure to add the oil gallery plugs front and rear. Failure to add or properly install the plugs can turn into a nightmare trying to find out what happened to your oil pressure after a full assembly has been completed.
Add the main studs to the block with a healthy dose of oil on the threads. All steel items, whether they're pressed in or threaded, need oil to keep them from gaulding and tearing up the aluminum threads in the block. Make sure #3 and #4 mains get special ones with extra threads for windage tray and oil pump pickup. After using special body shop lint free pre-cleaning cloths, dabbed in ATF to clean the bores, clean the bearing surfaces with a good evaporative solvent such as alcohol.
Unlike its small-block predecessor, the 4.6 engine utilizes the #5 or last main bearing to perform the thrust duties. Windsor small blocks were one of the only engines to use the center or #3 bearing cap. All of the upper bearings (with oil grooves and holes) are the same with the thrust washer being a separate one-piece 180-degree washer. At first it looks odd with the lower thrust bearing capturing both sides of the crank and the top just capturing one, especially since the GT 2V cast iron block uses both on top and bottom. We're not sure about their philosophy here, but it must work because it has never been the subject of any of the many engineering changes.
Push the crankshaft rearward when you're installing the thrust washer to create the proper clearance for the unit. Clean all main bearing cap surfaces with solvent and add the lower bearings to the caps. Push the crank back towards the front of the block to install the lower thrust bearing main cap. Install the rest of the main caps and stud nuts with lots of oil.
The ARP studs do not use the factory's torque to yield (TTY) method, which involves a final turn of 90 degrees after the final torque wrench setting. However they do still use the factory tightening sequence with the outers getting 30 lbs.-ft. and the inner 60 lbs.-ft. "We use ARP for the entire engine; the ARP studs have a much higher 130,000-lb. tensile strength, which is far better than the factory stuff." John told us.
The crankshaft endplay is then checked to be within the .005-.015 factory setting. We then add the side adjusting screws, checked the endplay, add the side bolts and checked it again. Give the crank a few turns to make sure you haven't put it in a bind while pre-loading it. A methodical approach to properly secure the crankshaft in a free state will assure your stroker engine a long life.
Now it's time to assemble the piston and connecting rod assemblies. The stock pistons' pressed in wrist pins use a retaining ring where the full floating type of the stroker kit uses double (meaning two locks per side) spiral locks. They come flat and you pull them apart, so they look like a spring before installation. This locks them into the ring groove and makes them very easy to install.
At SHM, pre-torquing the rod bolts is always standard procedure as they have, on rare occasion, gotten bad bolts. After placing the connecting rods in a rod vise and torquing in several steps until the .005-.006 stretch is obtained, the specific torque settings are noted. They will be used when the rod assemblies are installed on the crankshaft, assuring the optimum settings are utilized. (Usually around 70 lbs.-ft.) This is always recommended by the manufacturers as added assurance of the bolt's proper heat-treat process.
Each ring is carefully placed squarely in the bore and checked with a feeler gauge then precision-ground to obtain its respective target gap. Then you carefully add the rings to the pistons, noting the exact location of the gaps in accordance to the included manufacturers' spec sheets. Use a ring compressor to install the piston and rod assemblies in their respective cylinder by the numbers and arrows on the rods. Torque them on the crankshaft to the pre-recorded spec from the bolt-stretch operation. "We like to snug them all, then torque them to spec after they are all on the crank," explained John. Check rod side clearance after the torque procedure by prying both rods to one side, then check the gap with your feeler gauges-it should check .005-.017. Next add the windage tray with the standoffs and torque them to 100 lbs.-in.
Now this is definitely the coolest engineering feat of the modular motors: the rear seal retaining cover. It contains a one-piece seal that presses into the cover. You just add some petroleum jelly to the seal and a bead of silicone on the mounting surfaces, as it doesn't use a gasket. On the other end, install the oil pump gears to the housing and torque the lid to 100 lbs.-in. It doesn't need silicone because it has an O-ring groove around the housing for, you guessed it, a huge O-ring.
We always recommend adding a dab of red Loctite on the pick-up tube bolts then torquing them to 89 lbs.-in. and the pick-up brace bolts to 20 lbs.-ft. Always replace the O-ring in the pick-up tube where it mounts to the pump. Install the oil pan and torque to 24 lbs.-in. The factory gasket comes with cool little steel grommets built in to prevent the bolts from over compressing the gasket.
This assembly process applies to any '95-98 4.6 4V Cobra engine short-block. Hopefully you've found some helpful tips to aid in assembling your project or maybe just to teach you exactly what makes one of these Modular motors tick.
Next month we'll take the mystery out of installing the timing chains and how they work. We'll also bolt on the cams and install the lifters and rockers, and, finally, "The Tale of the Tape" will be revealed, as we get a readout from the dyno test of the big Sean Hyland 5.2 Stroker Modular Motor.