There is perhaps no fighter plane more American than the A-10 Thunderbolt, affectionately known as the “Warthog.” Similarly, there is no sports car more American than the Chevrolet Corvette. What ties those two icons together is NASA MidAmerica racer Jim Macaulay, who is a retired A-10 pilot and current pilot for the 1973 Corvette you see here.
Macaulay was attending an air show back in the 1990s talking with another pilot, who told him he raced a 1969 Ford Mustang Boss 302. Macaulay assumed he was talking about drag racing, but when heard it was road racing, Macaulay went to Texas World Speedway to flag as a corner worker for a weekend.
“I worked a corner there and saw the racing and I said, ‘This is for me and this is what I got to do,’” he said.
Macaulay set about finding a car suited to his liking that he could use for road racing. All this was taking place in the year 2000, when finding a car was not as easy as it is today, but Macaulay found this 1973 Corvette on the Texas/Oklahoma border.
“I went out there and it turns out it was a father who bought it for his teenage son, and the teenage son got into a lot of trouble with the car. And so as punishment, he was going to sell the car,” Macaulay said. “We made a deal on the spot and I actually drove it home. It was just a base model Corvette. It had speaker holes hacked out of just about every metal structure in the car. And it was definitely a 17-year-old’s car. So I brought it home and I proceeded to build the car into what I thought would be a racecar.”
New to racing, Macaulay was trying to walk the fine line of modifying the car for racing, but doing so in such a way that it could be undone and returned to road-going status. All of you nodding your head right know the folly of trying to build a dual-use car, and it didn’t take long for Macaulay to figure that out for himself and make it a dedicated racecar.
The first thing to go was the automatic transmission. In its place, a Muncie four-speed dropped right in. Macaulay simplified the wiring harness and refreshed the stock block with forged internals. He installed a big, lumpy flat-tappet cam, a pair of reworked “double-hump” cylinder heads, an aluminum intake, Mallory ignition system and some stainless headers. The result is an old-school small-block Chevrolet that makes 350 horsepower and a stump-pulling 400 pound-feet of torque.
Bringing it all to a stop is a factory four-wheel-disc braking system, which Macaulay said was required under vintage racing rules. Now, a stock braking system from a car from 1973 might not sound all that prodigious, but it’s helpful to know that the 1968 to 1982 Corvette came from the factory with four-piston calipers front and rear. All Macaulay did to modify the braking system was to add the right brake pads, and add cooling ducts where the turn signals normally would be located at the outer edge of the grille. It also helps that the car only weighs 3,050 pounds with the driver onboard.
For suspension, Macaulay’s Corvette is equally simple. The car uses Bilstein shocks all the way around. Up front, Macaulay took a set of 550-pound springs from a big-block Corvette and cut a couple of coils off them, and added a tie bar between the shock towers to stiffen up the chassis. In the rear, the car still uses the stock transverse seven-leaf spring. Macaulay lowered the rear by using longer bolts at each end of the leaf spring.
If all that sounds, well, rudimentary, take a look at the photo from Ozarks International Raceway’s Turn 11. It corners as flatly as any modern car. Notice how planted the inside front wheel is. It’s also worth noting that this 50-year-old car’s power-to-weight ratio allows it to slot into Super Touring 2, the same class where the modern C5 and C6 Corvettes.
“It’s pretty benign as far as racecars go,” Macaulay said. “But I guess if I could give the elevator pitch it would be that Corvette actually makes a pretty good car for the track right out of the box, and the modifications you do to it, just enhance it a little bit. But you got to be careful you don’t screw up what the engineers designed because they did a pretty good job when they were designing the car.”
After Macaulay removed the air conditioning and power steering and other unnecessary components from the front of the car, the front-to-rear weight distribution was 51/49. The C3 Corvette has a long front section, but the engine is placed behind the centerline of the front axle, which is part of why the weight distribution is so good.
The 1973 model is unique in the Corvette world. It has the chrome bumpers in the rear like the 1968-1972 models and the Enduraflex front bumper used in the front on the 1973 to 1979 models. As unique as the 1973 model is, its performance was hampered by emissions standards of its time, and it is not one of the more highly prized model years. Macaulay fixed all that, and wound up with a fast racecar for about $10,000 all in.
Macaulay races the car with Heartland Vintage Racing, and with NASA MidAmerica as a guest group. The spillover benefit is people come out to watch the vintage cars and are curious to know how they can get out on track. Macaulay credits Donna and Randy Lane for giving him and other vintage racers are place to race.
“I can’t give her enough props. She invites us to come out and race with them,” Macaulay said. “But we have our own race group, and it’s a great synergy because people love the old cars. People come out to the NASA races just to see the vintage cars and then they say, ‘Hey, I can race my streetcar out here and go through the HPDE program.’ And so if we bring in people to see the old cars, it may translate into new HPDE drivers. So it works out pretty well. I think NASA MidAmerica, Donna said they grew by over 30 percent last year, which is great.”
Macaulay’s career as an A-10 pilot is certainly helpful to him on track. He flew in combat in the first Gulf War, in Bosnia and Kosovo and trained pilots for combat in Iraq and Afghanistan. There are similarities between the two.
“In the A-10, our primary mission is ground attack and supporting the guys on the ground, and we love doing that. But a secondary mission is air-to-air, what we call dog fighting, which all fighters have done since World War I days,’” Macaulay said. “And where you’re maneuvering in relation to the other fighters, you’re trying to negate their advantages and exploit your own advantages, capitalize on their weaknesses or their screw-ups, those kinds of things. That’s kind of what you do on the track. There’s guys are going to be faster than you at certain places. You’re going to be faster than them, and you got to figure out how you can exploit and take advantage of yours and minimize his.
“You’re pushing your aircraft to the limit, just like you’re pushing your car to the limit doing basic flight maneuvers, I mean, lift and traction are pretty much the same,” he added. “In an airplane. You get on the edge of lift and you stall, and in a car you get on the edge of traction and you touch the envelope, push it just a little bit, and you slide or spin if you go too far. So the energy management is big, managing your speed, momentum, ability to stop, slow down, accelerate, all those kind of things you do in airplanes, you just do it in three dimensions versus the two on the track.”
| Owner: | Jim Macaulay |
| Year: | 1973 |
| Make: | Chevrolet |
| Model: | Corvette |
| Weight: | 3,050 lbs. with driver |
| Engine/Horsepower: | Chevrolet 350, 382 rwhp |
| Transmission: | Stock Muncie M-21, close ratio |
| Suspension Front: | Stock – 3/4 coil, Bilstein shocks |
| Suspension Rear: | Stock 7 leaf spring, Bilstein shocks |
| Tires Front: | Hoosier 25.5×8.5×15” Bias Ply |
| Tires Rear: | Hoosier 26.5/9.5×15 |
| Brakes Front: | Stock 11” Disk |
| Brakes Rear: | Stock 10.5” Disk |
| Data System: | 62 year old brain |
| Sponsors: | Natty Light can rebates |
