“The horsepower stuff that Ron [Pryor] brought to the table that’s in the car was all him, not me,” Derek Hall says. Pryor chose the 620-horse version of GM Performance Parts’ ZZ572. But before he installed it, he commissioned Spokane Valley’s Dave Viall to reassemble it to finer specs. Typical for these engines, it swings 4.560-inch forged pistons on a 4.375-inch forged crank. Those pistons with the alloy heads’ 118cc chambers yield a 9.6:1 static compression ratio. The 254/264 0.050-inch duration specs on the supplied hydraulic roller-tappet cam mean the engine makes at least GM’s rated output: 650 lb-ft of torque at 4,500 rpm and 620 hp at 5,500. Pryor topped the supplied single-plane manifold with a Proform Parts Street Series 850-cfm carburetor. Shawn McCarthy at SMC Customs built the 21/4-inch headers on the yonder side of the heads. McCarthy also built the MagnaFlow-muffed 3-inch-diameter pipes that they feed. A March Performance accessory-drive system spins a March P570 alternator, a Sanden refrigerant pump, and a GM HP Deluxe aluminum water pump. That pump feeds a Be Cool alloy radiator. A pair of that company’s high-torque fans ensures respectable airflow at low speeds. Billet lettering softens the otherwise austere image of the sheet-aluminum ZZ Custom Fabrication rocker covers. The conventional HEI ignition between those covers distributes spark to Taylor 8.2mm wires. Coupled to the engine by way of a McLeod bellhousing is a Tremec TKO 3550 prepped by A.J. Kautzman in Spokane Valley. A modified pedal assembly commands a McLeod clutch. A Hurst stalk, tailored by Hall so Duval’s hand falls to it, selects the transmission’s gears. A driveshaft made by Spokane’s Watts Wheel and Driveline transmits the drivetrain’s copious torque to a 3.73:1 screw bolted to a Detroit Locker carrier. It spins a pair of 31-spline Strange axleshafts in a housing of the same make.
You’re not likely to encounter wheels like the ones Hall used on a muscle car and it’s far from accidental. The wheels Boss Motorsports makes usually find homes on late-model sport-luxury cars but its Model 338 wheels borrow heavily from traditional five-spoke hot rod designs. The front wheels measure 18x8 and maintain a 4.5-inch backspace; the 18x9.5-inch rear wheels have a 5-inch backspace. They wear Uniroyal Tiger Paws, 245/40 and 285/40, respectively. They bolt to vented and cross-drilled 12-inch (rear) and 13-inch (front) Wilwood rotors. Arresting those are six-piston Wilwood calipers.