496ci Short Block Build - Big Heat
Building a 496ci Short-Block for the Tarmac
From the May, 2012 issue of Chevy High Performance
By Henry De Los Santos, Sean Haggai
Photography by Henry De Los Santos
The potential for making a ton of twist is merely a game of cubic inches and compression. In other words, the more cubic inches you’ve got to pack air and fuel into, the more power you’re going to make.
Lucky for us, our favorite big-block hasn’t changed much since its inception; it’s what helps keep most of us well within our budgets when building a potent mill for the track. Combine that with what the aftermarket has to offer and you have the perfect recipe for making a whole lot of grunt with big bore, big stroke combinations. Since big-blocks already have the advantage of a larger footprint, piecing one together for the strip is a no-brainer and a guaranteed torque monster.
As with any serious build, setting the appropriate groundwork lies within the unseen players. Feed a freshly machined block the right rotating assembly from the get-go and the potential for power is nearly limitless. It really comes down to the prep and installation of bulletproof components for a mill, and it has to have enough guts to last and pull any old-school or late-model favorite to the big end. The biggest challenge is selecting the right components to perform round after round.
For this build, we went to Dr. J’s Performance in Anaheim, California, where owner, Bryce Mulvey took us inside the belly of our 496ci short-block build. Inside, our key players included a complete forged Scat rotating assembly with a 4.250-inch stroker crankshaft and 6.3850-inch rods. To back it all up, we installed a set of big domed forged JE pistons. At the heart of our freshly machined two-bolt main big-block is a high-lift COMP Cams solid-roller setup with matching lifters and an adjustable billet timing set. Follow along for the complete details and the next time you see our short-block, we’re planning to follow it up with a complete Brodix STS Race Rite BB-2 top end.
Scat forged standard weight crankshafts are designed for street or race engines with substantially increased horsepower. Scat crankshafts are precision-ground, heat-treated, shot-peened, inspected, and micro-polished at Scat for superior tolerance control. Scat crankshafts are also nitride-hardened for superior wear resistance, have straight-shot and chamfered oil holes, and feature lightening holes in all rod throws. These crankshafts also have a large radius on all journals for improved strength and wear resistance.
Scat Crank Specs
|Rear Main Seal Style
||Forged 4340 steel
|Rod Journal Diameter
|Crankshaft Snout Style
|*All measurements in inches
Scat’s forged 4340 H-beam connecting rods are strong and perfect for power adder and high-compression combinations. These rods incorporate a special doweled cap for specific cap-to-rod alignment, profiled with extra clearance for stroker applications, and come balanced and weight matched as a set.
There are a number of options...
There are a number of options when it comes to locating an adequate block for the job. For us, the decision to use a Gen IV two-bolt main block was easy. These blocks are plentiful, take a ton of abuse, and are easy to find. We added in a new set of ARP main bolts for added strength, helping us to up the stakes on making a reliable track performer.
Before we could add the goods,...
Before we could add the goods, we first had our block fully prepped and machined. Since this was a seasoned block, we only needed to clean up the bores with a fresh hone. We removed about 0.005 inch with our final bore size coming in at 4.3105 inch.
Bryce measured each bore for...
Bryce measured each bore for piston-to-wall clearance; we were safe with 0.005-inch clearance.
For rod bearing clearance,...
For rod bearing clearance, Bryce Mulvey checked each rod with a bore gauge before they were installed onto the pistons. Our gauge showed just the right amount of clearance at 0.003 inch.
To hang the pistons, Mulvey...
To hang the pistons, Mulvey applied a small amount of engine assembly lube onto the wristpin and slid it through. He then locked in the pins with the Spiro locks. Note: If the pins do not install easily, the piston may need to be honed out to provide enough clearance for the pin.
For our high-compression drag...
For our high-compression drag race application, we relied on a set of JE pistons. These pistons feature an open chamber with a raised, 43cc dome. Each piston also features JE’s precision-cut CNC-machined grooves and accept 1/6-, 1/16-, and 3/16-inch rings. Included in with our set of pistons were wristpins, double Spiro locks, and double pin oilers.
Scat Rod Specifications
|Connecting Rod Length Center to Center
|Connecting Rod Bolt Diameter
|Rod Journal Diameter
|Big End Bore Diameter
|Pin End Bore Diameter
|Big End Width
|Duration at 0.050
|Lobe Separation (degrees)
|Basic rpm Range
|Intake Duration at 0.050-inch Lift
|Exhaust Duration at 0.050-inch Lift
|Advertised Exhaust Duration
|Intake Valve Lash
|Exhaust Valve Lash
For the proper ring endgap,...
For the proper ring endgap, we used a ring filing tool with a grinding disc.
It’s important to mention...
It’s important to mention that rings should always be filed from the ring face toward the inside diameter to avoid damaging the face coating. Mulvey made sure to keep the endgaps square and filed until we achieved our desired 0.0032-inch ring gap. Then, we simply smoothed over the rings to remove any sharp edges or burrs.
Before installing the crankshaft,...
Before installing the crankshaft, Mulvey installed each main bearing by matching the bearing tangs with each saddle in the block. From there, he applied a small amount of engine assembly lube to each main bearing.
These COMP Cams Elite Race solid-roller lifters are trick and come with a myriad of features. Some of these are the exclusive body design that don’t include an oil band, which maximizes rigidity and reduces lifter bushing wear. The body is manufactured from CNC-machined SAE 8620 steel alloy, with steel alloy wheels that have been micro-polished and micro-sized and needles that are made from 52100 bearing steel and micro-sorted with a controlled contour profile. While the construction and body design make them incredibly strong, they are also lightweight, with each lifter weighing less than 100 grams. They also have oversized (0.400-inch) axles that are dual-pinned, have captured link bars and an exclusive modular pushrod design that allows the pushrod insert to be swapped out for centered, left, or right offsets. These lifters also have a patent-pending oil control through the pushrod insert; engine builders can modify the lifters to meter extra oil to the top as desired.
Once the crank was set into...
Once the crank was set into place for final, Mulvey placed each cap onto the block to lock in the crank. Then, beginning with the center cap and working outward, he torqued each cap down to 105 ft-lb, using a 1/2-inch socket. We made sure to apply a healthy amount of ARP Ultra-Torque assembly lube to each bolt prior to threading it into the block. Afterward, we gave the crank a good spin to make sure there was no binding.
Beginning with the first bank...
Beginning with the first bank of cylinders, Mulvey installed each piston and rod into the bores. Then, placed the rod cap on and torqued each rod combination to 65 ft-lb.
If you’re looking for more...
If you’re looking for more than just a streetable cam, COMP Cams has designed a drag race cam for you. While we’ve included the specs below, these cams are specifically designed for all-out dragstrip performance on 468ci mills and larger, and will fit nicely with our high-compression pistons. These cams do, however, require a thrust button with a wear plate and an aftermarket distributor gear.
To complete our short-block,...
To complete our short-block, we installed COMP Cam’s Ultimate Adjustable Timing set. The COMP two-piece billet steel cam sprockets allow cam timing changes without removing the degree wheel or releasing the valvetrain load. Timing can be varied from 6 degrees retarded to 6 degrees advanced, and there are no cam bushings to break either. The chain is also a heavy-duty, double-row type with large 0.250-inch rollers and the kit even includes the roller thrust bearing with custom adjusting tool. For our setup, Mulvey installed the camshaft straight up. With 4 degrees already degreed into the cam from COMP, which put our intake centerline at 106 degrees.
Future upgrades are inevitable...
Future upgrades are inevitable and building it correctly from the start will prevent any unneeded teardowns for additional power later on. For now, we have a solid start on our 496ci big-block build. We’ll have the Brodix top end installed shortly and then we’re off to the dyno to see what this big-inch mule will produce. CHP