When Ed Davis originally bought his 1958 Vette, he wanted to go racing—sports car racing, at his local Southern California tracks. With tuning by Geraghty Automotive and skilled driving by Cal Bailey, Davis’ Corvette “broke and held track records at both Santa Barbara and Riverside road race courses,” wrote John Geraghty in the July ’61 issue of Car Craft. “Then Ed’s interest turned to drag racing, where he could compete in the cockpit.”
The stock-class trophies “came easy,” Geraghty wrote, but Davis wanted to go faster. So he and Geraghty mapped a plan to build a supercharged small-block to go hunting in the B/Modified Sports class. Rather than modify the Vette’s original engine, they put together a mill that would both make power and withstand the pressures of forced induction.
Their starting point was a used ’57-’60 block that got a few thousandths shaved from the bore for cleanup and piston-to-wall clearance. The reciprocating assembly consisted of a 0.25-inch C-T stroker crankshaft, C-T boxed rods and Forgedtrue pistons. To keep the bottom end from leaving the car under boost, the main caps were reinforced with 7⁄16-inch steel straps. Geraghty also improved cylinder head sealing by cutting O-ring grooves into the block so he could augment the head gaskets with 18-gauge wire in the grooves.
Geraghty used ’58-’60 fuelie heads, chosen for their lower compression and water-cooled spark plugs, and then ported them before installing the oversize valves. Jack Engle of Engle Cams chose a cam grind optimized for the supercharger: a 4-71 GMC unit pushing about 11 psi of boost. Fuel was introduced through a Hilborn injection system, and the spark was lit via a Scintilla magneto.
Backing the engine was a Turbo-Hydramatic automatic modified by B&M, which also supplied the shifter and linkage, designed to “allow much more sensitive feel of each gear selection,” wrote Geraghty. A shortened driveshaft transmitted power to the Vette’s rearend, which was fitted with 5.17 gears and wore M&H Racemaster slicks.
With this combination, Davis ran 123 mph at the Pomona and San Fernando dragstrips, breaking records at each. His best e.t. was 11.88 seconds. “The supercharger ratio is now being increased, which will raise the manifold boost from 11 to 16 pounds,” wrote Geraghty. “This, along with the installation of a larger camshaft, is sure to increase the performance factor.”
In this state of tune, though, Davis was able to enjoy the car on the street (“…a desirable car to drive on the highway,” Geraghty called it) and the ’strip. “The handing characteristics of the Corvette Super Sport suspension and steering produce a trip down the quarter-mile that the driver can fully enjoy. The Candy Apple paintjob, offset by the white tonneau cover, makes this machine as pleasing to look at standing still as it is screaming down the ’strip.”