Buck selected his piston and rod combination, and built the engine combination to work aro
These internal components, from the small journals and piston pins, to the narrow-section Total Seal ring package featuring .031-inch compression rings and 1.5mm oil rings, are all designed for light weight and low friction. Hinkle found the rings, which work in conjunction with gas ports in the pistons, sealed well. The rods are pin-guided, which means that the running alignment of the piston/rod assembly is maintained by the piston at the pin, rather than at the connecting rod big-end cheeks, as is common with a production engine.
Expanding on the pin-guided assembly, Buck tells us: “It gives you less friction because the rods don’t touch anything; they are just floating on the crankshaft. They don’t touch the side of the crank, and they don’t touch the other rods, because the rods are really narrow. If you look at the side clearance, you have about .100 inch between the side of the rods and the crank, and .100 inch between the rods. You would think the oil pressure would go away, but it doesn’t. It hardly affects the oil pressure if you have the bearings right. The other thing it does, assuming everything is straight as far as machine work, is it keeps the piston exactly centered in the bore as the rod spins around. The rod isn’t pushed to one side by the other rod or the side of the crankshaft. That centers the ring-and-piston assembly as it goes up and down in the bore.”
Unlike a production engine in which the rod’s big-end cheeks keep the piston aligned in th
With the bottom end buttoned up with a standard Melling Chevy oil pump and a wet sump oil pan fabricated from a steel dry-sump pan, the rest of the engine combination came down to the cam and valvetrain and top end components. Buck bushed the lifter bores to fit the .875-inch Crower solid roller lifters. These Crower lifters feature a .180-inch offset on the intake side, which helps the geometry by putting the pushrod in better alignment with the rockers. To maintain low-end torque and meet the 7,500-rpm limit of the competition, Hinkle was relatively conservative when ordering the custom COMP solid roller cam. Specs on the cam are 249/253 degrees duration at .050 on a 108-degree lobe separation angle, with .756-inch gross lift delivered by the 1.75:1 T&D rocker arms. Buck relates: “It wasn’t really a big camshaft, but we were trying to get the torque down at the bottom. Everyone said to me that the SB2 doesn’t put out the torque, but I found out different.” The dyno results showed very strong torque right from the bottom of the test range at 3,500 rpm.
The pistons were built with grooves to take a very narrow .031 ring profile, which were fi
Up top, the cylinder heads are a key component in making serious power. The SB2.2 heads are a purpose-built race head and take advantage of a completely revised port and valve layout compared to a traditional Chevy small-block. These heads are former NASCAR units, and Hinkle Performance has had plenty of experience with the setup, building a number of these engine combinations for customers’ street cars. The heads were ported by Clark, showing 402 cfm on the intake side at just .700-inch lift. Buck explains: “I try to get the flow through the midrange as best I can—that’s where the valve is working the most. We used a 55-degree intake seat, with titanium Del West valves, a 2.160-inch intake valve, and 1.600-inch exhaust valves.” Buck considers the SB2 cylinder head an exceptional piece: “The way the heads flow and the combustion chambers are designed just works. When I dyno test those things they are just a step above any other small-block head you can put on; they just kind of explode with power once they come on.”