As ancient Chinese philosopher Lao-Tzu taught us, every great journey begins with one small step. Our feature car’s great journey began in the fall of 1966 when Clyde Wheeler, Vice President of Public Affairs and Public Relations for the Sunray DX Oil Company, allocated money to expand Sunray’s motorsports-marketing initiative. Sunray would go from sponsoring tracks and events in the Midwest to forming its own racing team. To that end, the company contacted Yenko Chevrolet to order a race-ready ’67 Corvette. They chose a Corvette because of its all-American image and because they wanted to win. They went to Yenko because it was the foremost high-performance Chevy dealership in the country and, perhaps more importantly, because Don Yenko could get them something that was officially unavailable at the time: an L88 Corvette.
RPO L88 was a road-race option package that Chevy offered for Corvettes from 1967-69, but it was not available in September 1966 when 1967 production began. Furthermore, it was not even eligible to race, at least not in FIA-sanctioned events, because the L88 engine was not yet FIA homologated at the time. Sunray wanted to open its ’67 season with the 12 Hours of Sebring, which then as now was the most important sports-car race in America, and perhaps second in importance throughout the world only to Le Mans. To get an L88 built in time for Sebring, some favors would have to be called in, and nobody was in a better position to get the job done than Don Yenko.
The Yenko family had been close with Ed Cole since shortly after Frank Yenko opened his Bentleyville, Pennsylvania Chevy dealership in 1927. Cole was an engineer with GM who shared some key things in common with the Yenkos, including an insatiable interest in aircraft and flying, and a love for high-performance cars. Despite having only a limited education and no engineering degree, Cole progressed steadily through the ranks, serving as head of engineering for Cadillac and then Chevrolet, general manager of Chevrolet and, ultimately, president of General Motors. In 1967 Don Yenko may have been the only Chevy dealer in the world who could telephone the president of GM to ask for a personal favor. He did, and through Cole’s initiative a Central Office Production Order (COPO) was written to build an L88 Corvette for Sunray DX Oil.
As with each of the 216 L88 Corvettes built from 1967-69, the heart of Sunray’s car was a potent 427-cubic-inch engine. Four-bolt main bearing caps anchored a forged, cross-drilled and nitrided crank. Forged steel connecting rods rode on special bearings, and 12.5:1-compression forged aluminum pistons were anchored with full-floating pins. To keep weight down, the engine’s rectangular-port, closed-chamber cylinder heads were cast from aluminum. From heat-treated rocker arms and strengthened springs to oversized valves and a high-lift, long-duration camshaft, the entire valvetrain was optimized for sustained high-speed operation and maximum power.
A small-diameter flywheel and clutch saved valuable reciprocating weight and helped the engine rev up relatively quickly for a 7-liter V-8. Induction came via a single Holley 850-cfm carburetor, perched atop an open-plenum aluminum intake manifold whose design was skewed toward generating peak output in the upper reaches of the rpm band. The carburetor was fed cool outside air courtesy of underhood ductwork that reached back to the high-pressure area at the base of the windshield. Spark came from GM’s reliable transistor ignition system, uniquely tailored for the L88 with heat-resistant Delco plug wires and a distributor without vacuum advance. An oversized aluminum cross-flow radiator delivered extra cooling capacity, and a special heavy-duty Delco starter motor cranked over the big, high-compression mill.
While a thundering 427 engine was the focal point of the L88 package, it was only one part of what turned an ordinary Corvette into a potential race winner. All ’67 L88 Corvettes were built with the M22 heavy-duty four-speed transmission, G81 Positraction differential, J50/J56 heavy-duty power brakes, F41 heavy-duty suspension and K66 transistor ignition. In addition to all of the components that L88 Corvettes had to have, there was also a list of things they could not have, including the otherwise standard heater/defroster system and “luxury” options such as a radio and air conditioning.
Besides the monster motor and the various heavy-duty parts that necessarily accompanied it, Sunray’s ’67 coupe was equipped with a variety of special components provided by Chevrolet Engineering. Among these were a unique header and side-exhaust setup, twin-pin rear brake calipers, light alloy wheels and a 44-gallon fiberglass fuel tank.