How do you build a 12-second 1968 Camaro? Bill Thomas made it sound so easy: “Well, we took this 425-horse 427 engine assembly, stuffed one of our 550 hydraulic cams into it, added a few handling pieces to the suspension and clamped on a set of tube headers, and the results sort of tear your head off.”
When Jim McFarland profiled this car for the March 1968 issue of Hot Rod magazine, Thomas was an old hand in the Camaro conversion game, having been one of the first to transplant a 427 into the ponycar soon after its 1966 introduction. And the 12.50/113.21 this Camaro turned at Irwindale Raceway was done, said McFarland, “with all the restrictive smog equipment yet devised for a Chevy still intact: belting, air pump, emission tubing and a 3911 Holley ‘smog type’ carburetor…and with 3.7:1 rear gearing, open headers, a set of Casler 8-inch cap, 28-1/2-inch-tall soft-wall tires and 5,500-rpm shift points. Could be that this combination will turn out to be the strongest street rig you’ll have an opportunity to drive this year.”
Chevrolet helped with the process, offering multiple leaves in the rear spring packs for the ’68 model year rather than the ’67’s monoleaves. Reinforcements were still needed to maximize traction, though. Thomas added traction bars and recommended extra welding to add beef around the rear spring perches. He also installed a 1-inch front sway bar “for greatly improved ‘feel’ of front-end activity,” McFarland said, and heavy-duty shocks all around.
The engine received Thomas’s RR-550 hydraulic camshaft; 2-inch-diameter, 36-inch-long headers dumping into 3-1/2-inch diameter, 10-inch-long collectors; Champion N9-Y plugs gapped at 0.028-inch; and timing fixed at 38 degrees at 3,000 rpm “with 10 degrees of this in the distributor,” McFarland said. “The transmission was a 2.56 1st gear Muncie with stock shift linkage, and a 10-1/2-inch street/strip Schiefer Rev-Lok clutch and flywheel assembly.”
McFarland made some three dozen quarter-mile passes in the car, which weighed 3,440 pounds (“spare tire and no driver”). On street tires and with the 427 capped, “the car netted a consistent string of 14.0’s, 102’s. This was, of course, with street tires and absolutely no bite,” though the torquey big-block was able to clean the clock of a Ram-Air GTO that fellow HRM staffer Eric Dahlquist was testing at the same time. “We found that the Camaro would open almost a car length of daylight lead during 3rd gear acceleration. It was impressive.” Open exhausts and the Caslers brought the car to its 12.50s, even with “grandma shifts and the self-imposed rpm limit of 5,500.”
Based on his experience working with the magazine’s ’67 Camaro project car the year before, McFarland felt it “perfectly safe to extrapolate this performance to determine what you could expect the car to do in serious competition.” By shedding some weight, swapping the rear gears to 4.88s, mounting wider slicks, “a little chassis attitude work” and upping the engine speed to 7,200 rpm before shifts, “this $4,000 street-legal car (we drove it on the street every day we had it) is capable of 11.30s and speeds in the neighborhood of 122 mph! And we recall when 13.50 would clamp down a victory in D/Gas almost anywhere in the country.”
Thomas “has everything you need for the package,” said McFarland, “and you can literally build the car over the phone when you’re ordering. As soon as the average performance enthusiast gets wind of the car’s potential, simple mention of the completed package will be strong enough to dent a fender. The car just wants to run.”