How Modern Tech Brings the Thunder in Historic Trans-Am V-8s

One of our favorite classes at the Rolex Monterey Motorsports Reunion pits ’60s and ’70s Camaros, Mustangs, Challengers, Javelins, Falcons, and, appropriately, Trans Ams, against one another just like when they originally hurtled the Trans Am series into popularity. The 5.0-liter pushrod V-8s thunder past 7,000rpm and the cars each exploit their particular powertrain or chassis advantages at different parts of Laguna Seca. This race is easily one of the highlights of Car Week.

When the race finished, we finally peeled ourselves off the trackside chainlink fence and entered the pits. We wanted to learn how closely these modern powertrains compare to their vintage counterparts and how they all stack up in relationship to one another.

We first spoke to John Hildebrand, who runs the 1964 Pontiac LeMans known as the Gray Ghost. “Probably the major difference between then and now is that we use roller cams,” said Hildebrand. “Other than that, the car is supposed to be as it was presented in the year that it raced.” Like their high-performance factory counterparts, the Trans Am engines of the ’60s used solid, flat-tappet lifters to actuate the pushrods. Today, as Hildebrand mentioned, they use solid roller lifters. The more aggressive ramp rate of the roller cam lobe allows the valve to flow more air with the same duration compared to a solid flat tappet cam. It also reduces friction at the lifter. Valves and valve springs are another area where modern parts are a boon. Most racers in the class today use lightweight titanium valves, which are easier for the spring to control, allowing for higher engine speeds without resorting to spring pressures that would tax the valvetrain, adding friction and the increased heat and wear that comes with it.

As the SCCA rules dictated in the ’60s, these cars must run no more than 5.0 liters of displacement. Race officials can pull a spark plug and check the displacement if something seems fishy. Cylinder heads must be factory iron, and everything must look period-correct. Hildebrand’s LeMans was raced in 1971, so it can use Ram Air IV heads. The heads on Hildebrand’s car are not only the same casting number, they’re the actual heads that were raced in the ’71 season. His 303-cubic inch Pontiac V-8 is a de-stroked 400, meaning he’s got the advantage of using a bigger bore than some competitors. He is forced to use smaller front tires than the car did in 1971, though. It’s also down a bit on power compared to the top performers in the class, making just a bit less than 500 horsepower. “It’s got an Edelbrock P4B on it, which is probably the crappiest aluminum dual-plane you could possibly use,” he joked. Aftermarket parts have come a long way since then.

Peek under the hoods of the cars lined up in the Trans Am pits and you’ll see a variety of OEM hi-rise four-barrel intakes. Some Chevy drivers use the GM-supplied dual-four-barrel cross-ram, and others use vintage aftermarket pieces that look almost exactly like the factory pieces. Some even modify more modern intakes to look the part. There seems to be a bit of leeway though, as the choke point of all of the various brands of small-block seems to be the cylinder heads, and that’s where most of the effort is spent.

“The Boss 302s, I think they make way more power than they did back then,” said Hildebrand. The Boss 302s are known for having monster intake ports. It’s common for engine builders to fill the bottom of the cylinder head intake port with epoxy to increase the short side radius and make the turn into the combustion chamber more gradual, reducing port volume but increasing the velocity of the incoming air.

Chad Raynal, who campaigns the #64 1969 Camaro and works with plenty of owners and racers with pushrod small-blocks in other classes, backed up Hildebrand’s assessment. We asked him what kind of horsepower these V-8s are producing. “The Boss 302s are probably the best,” Raynal said, “they’re making 500, maybe as much as 515. Some of the Camaros are just at 500. The low end would be an early 289 Mustang that would probably be in the 430 to 450 range, but they’re very light.”

We asked Raynal if any Ford tunnel-port cars were running. There are a few of them that compete, but none were in attendance that weekend. The 1968 Ford tunnel-port head featured an even larger intake port than the later Boss 302s. Rather than squeezing the intake port between the pushrods, it used a huge intake port with the pushrod running right through the middle. The tunnel-ports have a bit of a reputation for being lazy at low engine speed, but Raynal told us there are a few engine builders who can make them work well on the track and the street, and he put us in contact with one of the best: Tony Oddo Jr.

Oddo runs T.O.E. Performance Products in Suisun City, California, and has been building engines for decades. His shop had 40 or so V-8s running at Laguna Seca that weekend, and several racers told us he was the authority on building performance pushrod engines. He sat down with us and let us pick his brain. We asked him about the camshaft duration these engines typically run. “Boss 302s like more duration on the exhaust than the Chevrolets do. A Chevy will be like 260/264, and the Ford Boss 302s will be around 260/274,” said Oddo. He’s referring to degrees of cam lift, measured at the point where the valve is open .050 inches. “The Boss 302 is such a big intake port that it’s gonna flow more than the small-block Chevy will.” Peak power comes at about 7300-7400rpm. Because they have to look the part of a vintage engine, valvetrain part selection is a bit limited. “Some of the engines are running shaft rockers if they can fit them under the stock valve covers,” said Oddo. Otherwise, lots of the Chevy engines use 1.6:1 Crower stud-mount roller rockers.

We asked Oddo how the power levels compare between the different brands of engines. “The AMCs are really close to the Chevys and the Fords,” he said. “The only Pontiac I’ve done was an original 303 Pontiac for the Trans Am series. They only made five or seven of the things and it was really down compared to everything else.” What about the Mopars? “We have to use a stock casting,” Oddo said, referring to the cylinder head. His process includes welding the exhaust ports to get rid of the dog-leg shape and converting them to a W2-style. He uses offset rocker arms so that he can widen the pinch point of the intake port as it squeezes between the pushrods. “With a lot of work, I can get similar power,” said Oddo.

Next, we asked Oddo about crankcase ventilation, as we saw lots of large-diameter tubing and hoses for the breather systems, but Oddo said it was not a concern. “Typically just a single -10 is enough. Some guys run two -12s just because that’s what they ran back in the day,” he said. “The biggest thing on one of these road race cars is to have a good oil pan,” explained Oddo. “We use a lot of Aviaid stuff.” The pans have oil control trap doors that keep the sump submerged and they also use plenty of oil which helps keep the temperature down. Most Trans Am engines run about eight quarts and some run as much as 10. Oddo sets up his Chevy small blocks to run 60psi of oil pressure when the engines are up to temp and running full-tilt. We also noted that lots of racers used a remote-mount oil filter. They not only make oil changes easier, but they also free up room in a critical area that makes it easier for the header and steering linkage to coexist.

For the Chevys, desirable and class-legal heads are not that hard to find, but it takes plenty of skill and effort to get the most power out of them, with a deft hand at the grinder making the most out of the vintage parts. Raynal told us that Valley Head Service, the same shop that worked on heads for some of the original GT350s, worked on some of the cars in the Trans Am field. However, as much as these drivers want every advantage they can get on the track, running an engine at the ragged edge isn’t worth the hassle. As one example, Oddo told us the camshafts aren’t using the most aggressive ramp rates. “These guys want to run and have no trouble, so we tend to overbuild them,” Oddo said. “If they miss a shift and over-rev to 8,400, usually it’s fine.” The improved parts, precision machining, and modern oil all add up to engines that last about 40 hours of racing before rebuilds. That’s something that crew chiefs could have only dreamt of when these cars were trading paint and gunning for the championship in ’70 and ’71.

These engines sound like vintage race engines, without a doubt, and it takes some scrutiny to find any flaws in their vintage portrayal once you pop the hood. They’re making similar power to racers of the era while also lasting much longer. The tricks used on these engines are the same ones hot-rodders have used since the ’60s and even before, but modern metallurgy and cutting-edge race parts have trickled down so that enthusiasts can get their hands on them. We, like Oddo, are grateful. “They didn’t have the type of component selection. Everything’s better,” said Oddo. Opening up a speed parts catalog or scrolling through the nearly endless parts available online makes us glad there’s so much at our fingertips and it gives us all kinds of ideas for building a vintage-looking engine of our own.