All photos courtesy of Borowski Race Engines
The credibility of “period-correct” engines can always be challenged in the court of public opinion; but, in the opinion of EngineLabs, this 327 Chevy recreation for a Cheetah continuation model has the right attitude.
The Cheetah, as many already know, was Bill Thomas’ idea of a Cobra killer in the mid-’60s. Chevy’s Zora Arkus-Duntov tested the aluminum-bodied (later models were fiberglass) speedster and even funneled some money into the early racing efforts. When GM shut down all official channels of race support and the Cheetah shop suffered a devastating fire, the project quickly died after only a handful of cars were built and delivered. Now, a company called Bill Thomas Motors is building continuation cars based on tooling designs copied from one of the original cars.
The block, crank and rods are from the '60s while the pistons are new.
This engine was built to power one of those cars and certainly follows the spirit of the times, but with a little extra kick. It was built about five years ago, yet never fired. The owner wanted to make sure it was ready for the Cheetah and asked Borowski Race Engines to check the parts and clearances and break it in on the dyno.
“The owner wanted as correct as possible but using more modern parts,” says Borowski engine builder Dave Livesey. That strategy makes sense, as 50-year-old NOS parts are extremely rare and the car itself wouldn’t be ’60s original.
The engine starts with a period-correct Corvette 327 block bored .030 over. Rotating assembly includes a GM steel crank and original rods upgraded with ARP bolts. The Speed-Pro pistons are contoured with a dome similar to the old Vette engines but compression ratio is down to 9.6:1 to run on pump gas.
A set of “492” angle-plug heads that were originally modified by Crane Cams are fitted with Comp Cams behive springs and roller-tip rockers.
“Back in the day you could send your heads to Crane and they would do a mild port job,” says Livesey. “It still works with a 1205 intake gasket, so it’s not super big. And it still has the 2.20/1.60 valve sizes.”
Motivating the valves is a Comp Cams Mutha Thumpr hydraulic roller camshaft with .533/.519 lift and 243/257 duration at .050.
“He was going for the sound,” says Livesey. “I thought it was too big for the motor but it ended up making more power than we expected.”
Induction is through a pair Edelbrock 500cfm carbs sitting on an Edelbrock C-26 dual quad intake.
“We had to do a lot of work on the carbs, playing with the metering rods and springs,” says Livesey, adding that the oil pump is from Melling and the Champ oil pan is close in design to the road-racing units used in that era. “It’s hooked up to a remote oil filter in the car.”
Topside are Edelbrock carbs and intake while a Champ road-racing oil pan revives memories of the original design.
Wrapping up the engine are vintage Corvette valve covers and a stock timing cover, which hides the double-roller timing chain.
Livesey took the engine up to 6,000 rpm where it recorded 388 horsepower.
“It was still climbing but we didn’t want to hurt the engine,” says Livesey, noting that peak torque was 350 lb-ft at 5,500 rpm. “A good ride would have taken it to 6,500 rpm. The torque curve was actually pretty flat with 335 at 3,500.”