You'd never know it by looking at the guy, but Steve Coombes has made a few bucks in his day. Although his successful business ventures afforded him the luxury of retiring at 54, he stands before us dressed in drab khaki shorts-most likely from Wal-Mart-and a quaint T-shirt, probably mooched off of his buddy for free. The well-weathered Toyota Camry he putts around town in is missing big chunks of paint in certain spots. Worst of all, we couldn't even scam a fancy meal out of him after our photo shoot, as we begrudgingly settled for fish and chips and cheap domestic beer instead. Rats. This isn't to suggest, however, that Steve is a tightwad. He just spends his money where it counts, which is especially true in the case of his 10-second '70 Trans Am. While it surely required a white-collar budget to fund its myriad engine combinations over the years, it retains a down-to-earth blue-collar feel.
Overall, the Trans Am is a beautiful machine, but it's far from perfect, and that's exactly the way it's supposed to be. The rock chips and assorted gashes on its paint aren't as much blemishes as they are badges of honor earned for excellence in road and track servitude over a span of two decades. Rather than putting his resources on pretty and trendy stuff, Steve's dedicated his time and checkbook to continually building new engine combinations and pounding the snot out of them. The Trans Am has had a total of seven different engine configurations, and even dipped into the 9s during one particularly mischievous phase. "I thrive on this stuff, so I have to build a new motor every two or three years to keep myself from getting bored," he explains. "Since it takes a couple of years to finish each motor, I'm constantly scheming up new combos."
Dismayed by the high price tags affixed to '69 Z/28s, he bought a '70 Trans Am for $5,500 in 1988. It still had the original Ram Air III 400 and TH400 trans. Despite the fact that it was a numbers-matching car in excellent condition, he didn't hesitate to throw on the mods. "I've had a lot of people give me a hard time about molesting a numbers-matching car, but I don't care about that sort of thing," he says. "I'm first and foremost a hot rodder, so numbers-matching or not, keeping a car original isn't for me. It's not like this car is a rare Ram Air IV or Super Duty car anyway."
During the restoration process, Steve's primary goal was maintaining a stock appearance. "I like Pro Touring and very much appreciate the technology that goes into those type of cars, but I'm a traditionalist," he says. "The car has evolved like it has because it was built to go in a straight line and cruise on the freeway, not carve up canyons. I even like the look of the small 15-inch wheels too." That evolution process started with minor restoration work that involved rebuilding the suspension and applying a fresh coat of paint. After that, the need to go faster led to the first in a long series of rebuilds.
After spotting an ad for some TRW pistons and Carrillo rods for $1,000, Steve thought it was an omen to build a new motor. He bored the block .030-over while retaining the stock crank, then added a mild hydraulic flat-tappet cam, 1.6:1 rockers, and 1 3/4-inch headers. Even with the stock heads, intake and Q-jet carb, the car consistently ran high 12s. Although it didn't last long, a new class e.t. and trap speed record was set by Steve at a local NMCA race in 1992, with a 12.85 at 105.3 mph. Granted, the combo was tame enough to drive every day, but Steve wanted 11s. He punched the block another .030-over, matched a set of ported factory D-port heads with an Edelbrock Performer RPM intake and a Holley 750-cfm carb, and installed a 251/262-at-.050 solid roller cam. The 412 produced 560 hp, and propelled the Trans Am to 11.45/118-mph e.t.'s.
By the time the third rebuild rolled around, Steve was ready to get serious with some jumbo cubes. Taking advantage of the interchangeability of Pontiac's engine architecture, Steve modified a 4.210-inch-stroke crank out of a 455 to fit the 400 block by grinding down its main journals, and yielded a total of 462 ci. Paired with an Edelbrock Victor intake and a massive 264/271-at-.050 cam, the motor kicked out 626 hp and 10.79/124-mph e.t.'s. At this point, Steve felt the numbers-matching block was being pushed to the limit, so he retired it from battle.
Following the tradition of improving e.t. by nearly a second with each rebuild, the next motor would prove to be the pinnacle of power and performance. Again, based on a production 400 block, it combined a 4.165-inch bore with a 4.1250-inch Crower billet crank for a total of 450 ci. Other tweaks included a switch to Edelbrock aluminum heads flowing 330 cfm, a beastly 279/287-at-.050 cam, and a Dominator carb. Good for a 10.36 at 129 mph at the track, the motor dyno'd at 699 hp. Nonetheless, Steve felt a four-tenths improvement over the prior motor wasn't anything to be proud of, so he hit it with nitrous until the car ran a 9.59 at 140 mph.
Here's where it gets interesting. Even though the Trans Am had a full interior and weighed over 3,700 lbs with driver, Steve didn't find it streetable enough for his tastes. The emphasis on improving streetability would serve as the theme from this point forward. Growing tired of mixing race gas into the tank in order to safely drive his car on the street, he detuned the next motor accordingly. "I always wanted to have a true street car that ran 10s naturally aspirated on pump gas, which is a lot harder than most people think," he says. "The goal was to make 600 hp at or below 6,000 rpm." Once again, he succeeded in his endeavors by building a .030-over 455 that used the same top-end components as his previous motors, but with a 254/254-at-.050 cam. The result was 600 hp and 10.88/124-mph e.t.'s.
Even with presumably nothing left to achieve, Steve still wanted more streetability and power, which brings us to the car's current configuration. Based on an Indian Adventures' aftermarket block with a 4.350-inch bore, the Trans Am's latest motor combo displaces 505 ci, thanks to a 4.250-inch Crower billet crank. It retains the same Edelbrock heads, and although the 260/266-at-.050 cam is a bit larger, the extra cubes help mask the additional duration. With an Edelbrock Performer RPM intake, the 505 produced 615 hp, good for a 10.99 at 123 mph at the track. Steve wasn't pleased with the car's performance, but attributes some of that disappointment to the brutal Texas heat. Since then, he's ditched the TH400 for a TH200-4R and installed a looser converter better suited to the motor's powerband. Likewise, swapping to a Victor intake was good for another 27 hp. We'll have to wait for updated track times (which is a real bummer), but what impressed us the most about the 505 is its shocking civility for such a potent naturally aspirated combo. It fires up, idles, and cruises as well as a finely tuned EFI motor, without a hint of bucking or surging.
Ultimately, building motors isn't cheap, and building seven of them requires the backing of a massive bankroll. That said, the aspect of the Trans Am that stands out the most is that it exudes none of the polarizing pretentiousness that typically plagues high-dollar hot rods. Regardless of the tax bracket you're in, it's the kind of car you not only want to build, but feel you can actually fabricate. Average people with average incomes can't help but feel a certain kinship with this machine, but what else would you expect from a guy who wears Wal-Mart shorts and a freebie T-shirt?
In an effort to reduce weight, Steve installed a fiberglass front clip and replaced the fa
In order to get the Victor intake manifold and an air cleaner to fit under the hood, Steve
By The Numbers
'70 Pontiac Trans Am
Steve Coombes, 60
Liberty Hill, TX
|Type: ||Pontiac 505 |
|Block: ||IA2 aftermarket block, |
bored to 4.350 inches
|Oiling: ||Melling oil pump, Canton six-quart pan |
|Rotating assembly: ||Crower 4.250-inch billet crank, |
Eagle 6.800-inch big-block Chevy steel rods,
forged 10.0:1 JE pistons
|Cylinder heads: ||Edelbrock Performer RPM |
aluminum castings ported to flow 330/250 cfm
at .700-inch lift, Ferrea 2.15/1.77-inch valves
|Camshaft: ||Crower 260/266 at .050 solid roller, |
.701/.680-inch lift, 110-degree LSA
|Valvetrain: ||Crower offset lifters, |
Sims Performance roller bearing retainer plate,
T&D shaft-mount rockers
|Induction: ||Edelbrock Victor intake manifold, |
Holley 950-cfm carb built by Precision Racing Components
|Ignition: ||MSD Pro-Billet distributor, coil, |
and Digital 6 box; Taylor plug wires
|Fuel system: ||Aeromotive A1000 pump, |
Mallory five-port pressure regulator,
Jaz 16-gallon fuel cell
|Exhaust: ||Hedman 2-inch headers, |
Dr. Gas 3.5-inch X-pipe collectors,
dual DynoMax 3-inch mufflers
|Cooling: ||Meziere water pump, |
aluminum crossflow radiator,
dual Perma-Cool electric fans
with custom shroud
|Output: ||642 hp at 6,000 rpm |
and 640 lb-ft at 4,600 rpm
|Built by: ||CHS Racing Engines (Austin, TX) |
|Transmission: ||GM TH200-4R trans, |
B&M Quicksilver shifter,
Earl’s trans cooler
|Rear axle: ||GM 12-bolt rearend, |
Moser 30-spline axles,
3.73:1 gears, Auburn posi
|Front suspension: ||Global West upper |
and lower control arms,
Edelbrock shocks, custom 1-inch sway bar,
Moog six-cylinder replacement springs
|Rear suspension: ||Landrum 300 lb/in leaf springs, |
CalTracs traction bars,
custom subframe connectors
|Brakes: ||Wilwood 10.75-inch discs, front; |
Wilwood 11-inch discs, rear
|Wheels & Tires |
|Wheels: ||American Racing Torq-Thrust D |
15x6, front; 15x8.5, rear
|Tires: ||Firestone 215/65R15, front; |
Nitto 275/60R15 drag radials, rear