1978 Chevy Corvette - Engine Of Desire

Repowering a '78 Indy Pace Car with a Ram Jet 350

Steve Temple Jan 11, 2012 0 Comment(s)
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The story of the '78 Indy Pace Car is a surprising one, with some twists and turns. Initially, this model was intended to celebrate the Corvette's Silver Anniversary, with a limited run of 100 two-tone, logo'd cars planned for each of the 25 years of production. Upon finding unexpected extra demand, GM eventually built one for each of the 6,200 Corvette dealerships instead. That tallied up to about 15 percent of the 1978 build total--much more than a "limited production run"--and was not to be confused with another '78 limited-edition Vette model that wore a 25th Anniversary paint scheme.

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Given the car's initial popularity, some unscrupulous buyers tried to pass off standard '78 models as factory Pace Cars. All it took was a black or silver car with the right options, along with a paint gun to apply the contrasting color for the two-tone treatment. That, plus a red pinstripe dividing the two colors, a couple of spoilers, special silver cabin trim, and thin-shell seats with extra lumbar support.

That's the story of the Pace Car in a nutshell. What hasn't been covered in detail, though, is how the car's drivetrain can be upgraded. That's the untold story we came across in Scott and Linda Walker's Pace Car.

Not one to rashly tamper with history, and being an ethical type employed in law enforcement, Scott is duly respectful toward the history of the '78 Pace Car. So in 1993, when the Walkers tracked down one just five miles from their home with only 3,000 miles on the odometer, they went to some lengths to restore it to near-new condition.

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The interior was in excellent condition, as was the body. Scott noted, however, that the engine was so dirty, it appeared that no human had performed any cleaning on it since it rolled off the St. Louis assembly line on April 28, 1978.

The asking price was $16,500, but after some negotiating the Walkers were able to acquire it for $12,000. Considering the original sticker price of the car was $14,385, they felt they got a great deal.

Later in the year, Scott detailed the motor and brought it back to a near-new appearance. He also joined the NCRS and worked hard to keep the Vette original as possible, through some diligent investigative work, in keeping with his professional training.

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"Whenever I found a low-mileage Pace Car, I would take pictures to document what color a part should be, or what sticker went where," he relates. Later on, he had a friend, Todd Harshman of O'Fallon, Missouri, repair all the stress cracks commonly found on the C3 Corvettes, then repaint the refurbished body.

"I believe it has a paintjob GM would have been proud of," Walker boasts of the finished product. "People are shocked when I tell them the car was painted in a garage. The Vette now looks great--but still original--and it's received numerous First Place trophies over the years."

With the car's cosmetics now in top-notch form, Walker soon came to an obvious conclusion regarding the car's period-correct drivetrain.

"While I loved the Vette, it was always lacking in horsepower," he admits. In 1978, the L82 engine was rated at 220 hp and recorded quarter-mile times in the high 15s at around 88 mph. That's hardly impressive compared with today's Corvettes, but in 1978 it could soundly thrash a Pinto.

Another reality check came when Walker thought of his Chevy S-10 pickup truck. Its 4.3 Vortec V-6 is rated at 240 horses, 20 more ponies than his beloved V-8 Corvette. He began to feel like he was carrying a Derringer to break up a gang fight. Seeking to increase the caliber of his street weapon, Walker began exploring ways to improve on its output with various power adders. Unfortunately, a blower or turbo would most likely require modifying the hood, something he wanted to avoid given the car's historically correct aesthetics.

One day he came across an article on the GM Performance Parts Ram Jet 350, in which it was noted how the engine was designed to look similar to the early Corvette fuel-injected mills. This plug-and-play, turnkey setup supposedly required only that a fuel pump be installed in the gas tank. Well, maybe.

"My only concern was that from the pictures it appeared that the [FI] doghouse would be too high for the hood," Walker observes. Turns out that his initial assessment was correct. When he contacted GM, he was told that the Ram Jet 350 would require a hood modification in order for it to fit in a '78 Corvette.

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Then VETTE magazine offered a potential solution, by featuring a '79 model with a C5 powerplant. Walker called the shop responsible for that project, and the manager put him in contact with another customer who had just dropped a Ram Jet 350 into his '78 Corvette.

After an hour of discussion with the owner of the car, and later reviewing photos of the project, Walker became convinced that he should arm his Pace Car with a whole new level of firepower.

Fortunately, prior to his decision, he had already installed a 700R4 overdrive transmission rated for output levels of up to 500 hp. This trans dropped the engine revs by 1,000 at 60 mph and allowed for both faster acceleration and improved fuel mileage.

Walker then assigned himself some more detective work, searching the Internet for a good price on a Ram Jet 350. He found one listed by a car dealership for $5,000 or "best offer." Being a streetwise cop, he low-balled the dealer and got it for $4,000. He then took it to Doug Johnson of Bar Racing in Maryland Heights, Missouri, who agreed to take on the installation.

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While Walker reports that it was a largely straightforward job, squeezing the Ram Jet into the '78 did require some modifications. The oil pan had to be switched out for clearance, while the aforementioned replacement fuel pump had to be capable of an operating pressure of 43 to 55 psi. Walker used a pump designed for an LT1 Camaro/Firebird, along with a 3/8-inch return fuel line.

In addition, Just Corvettes, owned by Dan Hughes of St. Charles, Missouri, provided a 1982 fuel-sending unit that Walker modified to accept the correct fuel pump. (The newer unit already has the wiring in place for the pump.) Walker points out that on '78 Corvettes, it's possible to remove the sending unit without dropping the gas tank. It only goes in and out one way, however, so you need to take your time.

GM also recommends using its heavy-duty starter (PN 10496870 for 12-3/4-inch flywheel/flexplate or PN 1876552 for a 14-inch flywheel/flexplate) as part of the swap. Again, Just Corvettes was able to provide the proper unit.

The computer for the Ram Jet is very small and can be easily secured on the firewall. An O2 sensor also has to be installed on the left exhaust pipe, right below the exhaust manifold. While GM recommends headers, Walker found that the original exhaust manifolds worked nicely and required no modifications, saving both time and money.

Once the Ram Jet was installed, it started up without any problems, but one issue became apparent right away. From time to time, the engine would run hot. Turning up the heater corrected the problem, at the cost of broiling the occupants' legs on hot days. Turns out you need to run a bypass hose from the water pump to the intake manifold, a modification not listed in the Ram Jet installation manual. Walker's astute detective work, along with a simple 6-inch piece of hose (never, ever used for getting miscreants to confess) solved the overheating problem.

As for the clearance issue on the top of the engine, even though he had spoken at length to someone who had installed a Ram Jet 350 in a '78 Corvette, Walker admits it was still a little stressful closing the hood for the first time. A ball of clay showed a mere half-inch of space.

After patiently enduring a 500-mile break-in period, he was able to realize the performance difference between the original L82/three-speed combo and the Ram Jet 350/four-speed setup. An additional benefit came in the area of fuel mileage, which increased from 14 to 24 mpg on the highway.

Initially Walker left off the cruise control because the throttle linkage on the Ram Jet is on the right side of the engine, but he later had a local hot-rod shop fabricate a mounting bracket for the cruise servo. A simple stainless-steel welding rod was then used to connect the servo to the throttle. He then ran the vacuum hose behind the firewall and through the mounting bracket, and once again had a working cruise control.

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The Ram Jet looks great in the Vette--almost like a factory option--and of course the performance improvement is vast. And while some insist that you should never modify a "classic" Corvette, Walker has a different take.

"By installing the Ram Jet, we were able to get the horsepower I'm sure GM would have liked to have in 1978," he says. Just in case, he wisely stored the original motor and transmission, so he can put the Corvette back to its pre-swap look without any problems.

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Still, having become accustomed to the newfound power and efficiency afforded by the injected engine, he admits, "I don't ever see myself doing that." And besides, when the hood is closed, this 350hp C3 looks very much like a stock '78 Pace Car. All of which means this cop's Corvette now packs a much-higher-caliber concealed weapon. vette

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