What is the key to finishing any off-road race? We're sure you're all offering a number of ideas here, but the team over at Dean Schlingmann Motorsports (DSM) in Covina, California, would claim durability at the top of any list. If it can't run for hours on end, be exposed to the gnarliest of environmental conditions, and still bring you to the finish line, it's just not good enough.
When their old 351 Windsor V-8 engine started showing its age, the team at DSM decided to step up and give the rest of the competitors in Class 8 desert racing something to be concerned with. Never ones to back down, DSM decided it was time to build a new engine for its F-150, which would prove durable for the seasons of desert racing ahead of them. It would have to provide enough power to propel their 5,200-pound lead sled (named Layla) across the deserts of Baja. But it had to do all this without breaking or breaking the bank.
After some intense research sessions and debates, team engine builder Steve Schlingmann decided on a 408 Windsor combination. The goal: 500-plus horsepower and 500-plus lb-ft of torque on pump gas. With these numbers, the team could be confident they would be the ones leaving other teams in the dust (providing no driver errors...) and would be crossing the finish line consistently.
True to their grass roots, the DSM team went to work hand-massaging the seasoned 351W block sourced from Mirage Parts. They first made sure to check for imperfections using both magnetic and chemical crack-checking methods. Next DSM hand sanded and polished the upper lifter valley to allow used oil in the upper end of the engine to find its way back to the pan quickly. Always looking for opportunities to extend engine life, team machinist Joel Oliva machined the area behind the water pump mounting face to house a 0.040-inch carb jet that was plumbed into the oil pressure signal line. This allowed the jet to spray the distributor gear with oil instead of relying solely on splash-oiling.
After receiving, every critical...
After receiving, every critical area of the block is chemically and magnetically checked for cracks.
After a few more rounds of cleaning and clearancing, DSM sent the block to anny Moreno for machining. Using Rottler equipment, Manny brought the deck to zero deck height (from crankshaft centerline), bored the cylinders 0.030 inches over and line-honed the cam and main bearing journals. Care was taken to mount and torque the main bearing girdle prior to any machining. Likewise, a torque plate was fastened to the block using ARP studs to eliminate any distortion during the machining process. Every cylinder and bearing journal was double checked for machining tolerance before the cleanup and initial assembly started.
After speaking with the guys at SCAT Enterprises, Steve decided on their 408 stroker assembly. At 0.030 inches overbore and a 4-inch stroke, the 408 stroker would provide sufficient power for getting the DSM race truck up to speed quickly. To match the torque goals while excelling in horsepower numbers, Steve called Air Flow Research to find out how they could help. Having recently introduced its Outlaw 185cc Aluminum Head, AFR was confident that the runner volume would allow for adequate torque numbers while keeping the air velocity high enough to sustain the horsepower goals DSM needs while charging across the desert.
The engine boring was performed...
The engine boring was performed using a Rottler machine for the highest quality standards
Never one to take components for granted, Steve went about checking each and every intake and exhaust valve spring for correct seat load at measured (and specified) height using a Rimac valve spring tester. Where seat pressure values varied, Steve used spring shims to preload the springs. While this technique may seem like overkill, comparing seat load pressure during future rebuilds will help to determine when springs are aging out of specification. To finish off the head work, Steve indexed the spark plugs using plug shims and port matched the Edelbrock Vic Jr intake manifold to minimize any air restrictions from the intake manifold to intake runners (Felpro gasket # 1263).
To ensure this 408 was benefiting from these improved head flow and cylinder volume numbers, DSM employed the experts at Comp Cams who helped to prescribe an aggressive cam using a solid roller lifter to follow (Comp Cams # 35-772-8). Additionally, Comp helped to spec its 1.6:1 Magnum roller rocker arms, 5/16-inch (0.110 wall thickness) push rods and double roller timing set to finish off the upper end.
DSM Machinist Joel Oliva machines...
DSM Machinist Joel Oliva machines the area behind the water pump mounting surface for the timing gear oiling jet.
The DSM crew meticulously cleaned every component as it was installed, making notes of critical dimensions and adjustments for historical comparison. As the crank was laid into the block, all crank bearing journals were measured before the Clevite Tri-Armor bearings were installed. Note: Clevite Tri-Armor bearings were a special request with this stroker kit at the preference of DSM. Plastigage was used to confirm bearing to crank clearance before liberally applying Torco assembly lube. True to the durability mindset, the rear main seal was pinned and safety-wired into place along with all freeze plugs. Main caps were fastened down with ARP studs specifically chosen to hold the 5/8-inch thick main girdle and windage tray in place.
Next, the SRP piston/H-beam forged rod assemblies were lowered into each cylinder and mated to the crankshaft. ARP fasteners were used to fasten the rod to the crank. To confirm proper fastener tightening, the "bolt stretch method" was employed using an ARP bolt stretch gauge. This stretch method would also allow for future fastener inspection and failure avoidance. Once installed, the piston deck height was confirmed. Using a Felpro 1011 0.040-inch head gasket, modeling clay was used on the top of the piston to help measure piston to valve clearance.
The oiling jet orifice is...
The oiling jet orifice is checked for accuracy by spraying brake cleaner through the jet onto the timing gear.
With clearances confirmed, DSM consulted with the experts at Ed's Auto Parts in Covina, California, to help prescribe all the correct gaskets, cam bearings, freeze plugs and brackets which would eventually be responsible for bringing this engine together. With the cam bearings installed, a liberal amount of Comp Cams assembly lube was applied to the cam before finding its home. To hold the cam in place, Steve chose to use the Comp Cams needle bearing thrust plate. This is a trick unit and highly recommended for similar applications. With cam end play confirmed, the cam was degreed using a set of rockers, a cam lobe lift gauge and a Comp degree wheel. The cam install was finished off by assembling the double roller timing gears and chain "straight up".
To finish up the assembly, Steve closed up the bottom end of the engine with an extra capacity oil pan. After torquing the heads, the valve lash was set for startup before applying the custom DSM valve covers. Between the valve covers, machinist Joel Oliva mounted -10AN breather fittings (sprint car style) which would eventually be plumbed to an oil catch can with blow-off filter to vent any positive crank pressure.
Hand-massaging off the upper...
Hand-massaging off the upper lifter valley allows for quick oil return to the pan.
Installing the MSD Pro Billet distributor required some modification to the distributor body and intake manifold. Twenty minutes of sanding and "clearancing" allowed for an easy install.
Trying to find a set of race ready headers for an F-150 proved challenging. To rid this stroker of spent exhaust gases, DSM utilized components supplied by Hedman Hedders to build a "one-off" custom set of 13/4-inch primary, long-tube headers. Measuring almost 36 inches in primary length, these headers helped to maintain torque while being easy to install. With a 3/8-inch thick head flange, warpage will not be a concern.
 Clearancing is required where...  Clearancing is required where the oil pump comes in close proximity to the main stud girdle. |  The cross hatch pattern in...  The cross hatch pattern in the cylinders indicates appropriate honing in preparation for the piston installation. |  Liberal amounts of Torco assembly...  Liberal amounts of Torco assembly lube are used on every bearing and friction surface. |
 The SRP/H-beam rod assemblies...  The SRP/H-beam rod assemblies are inserted into each cylinder using a piston ring compressing tool. |  Clearance is the name of the...  Clearance is the name of the game. Here, hand clearancing was required on the lowest portion of the cylinder sleeve in order to clearance the rotating assembly. |  The "bolt stretch method"...  The "bolt stretch method" was employed using an ARP bolt stretch gauge. |
 Each freeze plug was drilled,...  Each freeze plug was drilled, tapped, pinned and safety-wired in order to prevent plugs from escaping at the wrong time. |  The rear main seal and rear...  The rear main seal and rear cam plug were also pinned and safety-wired into place to avoid any blow outs. | |