Award-winning car builder Steve Strope of Pure Vision Design in Simi Valley, CA is known for incorporating unique powerplants into his creations. Examples include the DOHC Ford IndyCar engine-powered “Martini” Mustang and Bob Florine’s 1957 Ford Ranch Wagon with a big “Boss 9” engine from Jon Kaase. Strope’s most recent build is a 1966 Chevelle SS belonging to Habib Chababi. Strope replaced the factory 396 ci engine with a big-inch big-block that embodies a distinctive road racing flair with a quartet of Weber carburetors.
It stood to reason that Strope opted to collaborate with vintage road racing specialists Penta Motorsports in nearby Moorpark, CA for the build. Penta’s engine builder Doug Pearce has decades of road racing experience while Penta head honcho Steve Sanett, a long-time vintage racer, has become a “Weber Whisperer” of sorts.
The basic foundation of the build is your basic GM 454 truck block, which has been bored to 4.310 inches and incorporates a 4.375-inch-stroke forged steel SCAT crank for a total displacement of 511 cubic inches. A set of Autotec flat-top pistons are connected to the crank via Scat forged steel rods with ARP rod bolts, giving the “rat motor” a measured 10.04:1 compression ratio.
Edelbrock Performer aluminum heads with 2.190-inch intake and 1.880-inch exhaust valves are secured to the block with ARP 8740 chromoly head studs, while a set of Cometic MLS head gaskets provides the seal. A set of 1.7-ratio Speedmaster aluminum roller rocker arms activate the valves. The heads, block, valve covers, and accessories are powder coated “Chevrolet Orange.”
Sitting on top of the heads is a Borla intake manifold with four Weber 48 IDA carburetors that provide a combined airflow potential of some 2,500 cfm. However in reality the air intake is relative to the needs of the engine. One key advantage of employing the Webers on an individual runner intake manifold instead of one with a common plenum is excellent throttle response. It should be noted that Webers are very sensitive to fuel pressure and require far less than your basic Holley four-barrel carb. An Aeromotive fuel regulator, specially designed for low-pressure systems, is employed and adjusted to maintain 3 psi. The Weber air horns have been trimmed to facilitate hood clearance.
To optimize the potential of the unique intake package the Penta team collaborated with Isky Cams on a hydraulic roller cam that has .553 inch intake and .578-inch exhaust lift with a 228/238-degree duration at .050-inch and a lobe separation of 112 degrees. The goal was to optimize performance between 3,000 and 6,200 rpm.
Lubrication comes from a high-pressure, high-volume Melling oil pump, plus a Milodon oil pick-up and deep sump pan. The ignition spark is delivered from a Mallory distributor through Autolite wires and Autolite spark plugs. An “old school” look comes from finned cast aluminum valve covers and orange-hued components, while a Billet Specialties Tru-Trac serpentine pulley system takes care of all the pumps, A/C, and electrical power.
The net result is a distinctive-looking engine that backs up its competition flavor with crisp acceleration and tire-smoking power.