Mack Middleton assembled the 425 as a 438. The accessory-drive system Benchmark fabricated
Were it not for cost, Oldsmobile would’ve likely dominated GM’s sales through the ’50s. The second most powerful engine in the second lightest package in the lineup made the line of hot rod buyers too classy for a Chevrolet but not stuffy enough for a Cadillac.
One look at Duane Sorensen’s car suggests that Oldsmobile had more going for it than simply performance in 1956. When people parked by touch, a measure of a car’s brawn was its bumper, and the one on the ’56 Olds looks like it could swallow a lesser machine. The headlights flanking it were both menacing and cool, sort of like a gangster in a shark-skin suit, even the torch-tipped taillights bolstered the car’s rocket image. Forget your father’s Olds; this was a car his cooler younger brother would own. So it should come as no surprise that Duane Sorensen left the body of his ’56 Olds largely stock.
Trunk shots are generally rare in car features anymore but few trunks bear the detail this
Only he didn’t. Even a newcomer would notice that this car’s badges and handles went missing. And that’s only the start of it; Duane modified his Olds dramatically yet in ways that most die-hard fans wouldn’t notice—and as a former ’56 Olds owner I speak from experience.
The clue is the globe at the tip of the hood, or specifically its absence on this car. Designers planted it there to minimize a ponderously tall hood but curiously this hood looks perfectly comfortable without it. Why? Benchmark Fab and Finish in Corvallis, Oregon pancaked that hood.
To pancake a hood, if you didn’t know, is to flatten its profile. It isn’t easy; to do so requires cutting pie-shaped wedges from both sides of the hood’s entire length and re-shaping the dissimilar edges so they match. In this case Benchmark smooshed it 3 inches and leaned the upper edge of its face back 3-1/2 inches. It’s a ton of work for such a modest-sounding modification but it’s the occasional slap and tickle that makes Duane’s car stand out in such an understated way.
Custom materials aren’t a prerequisite for a custom car. Larry’s Upholstery preserved the
It’s worthy work if you’ve ever owned a ’50s Olds though; for as good as they are in some ways they’re frustratingly bad in others. For some reason Oldsmobile, Pontiac, and Buick clung to the same basic kingpin suspension from 1937-57. Ball-joint components from the ’58 cars can be adapted but Benchmark grafted a ’70 A-body (think Chevelle) GM frame stub instead. “The clip looks like it could be original suspension on the frame,” Duane says.
The shop improved the suspension’s already better geometry with SPC Performance Pro-Series adjustable upper control arms. Benchmark replaced the coils for shorter units, the antiroll bar with a 1-5/16-inch Hellwig unit, and the non-pressurized dampers with KYB Gas-A-Just pieces.
The Lecarra steering wheel is the most obvious change but it’s not the only one. Benchmark
They’re tough but ’50s Olds/Pontiac axles are also obsolete. Benchmark replaced it with a Ford 9-inch. It sports Dutchman alloy axles, a Trac-Loc limited-slip gear carrier, and a 3.25:1 gear. The shop retained the parallel leaf springs yet modified them for a lower stance. In anticipation of wider wheels it also narrowed the frame. Like the front, the rear sports KYB dampers and an antiroll bar. Eleven-inch Lincoln discs functionally match the front suspension’s 12-inch GM brakes.
Another trouble with Oldsmobile is its brake pedal assembly; it was designed for a treadle vac and doesn’t lend itself to conventional boosters or master cylinders. So Benchmark modified the pedal and its linkage to operate an electric booster from ABS Power Brake Inc. It, in turn, exerts its power on a dual-circuit master cylinder under the floor.
We love Boss Kettering’s Olds V-8 but we understand that not everybody is as willing as we are to bear the shortcomings of obsolete engines. Though the 425 Olds he chose is only a decade newer it’s well supported thanks to the engine’s presence through the muscle-car era. Renton, Washington’s Mack Middleton assembled a 438 with ported B-series heads. Benchmark-modified Hooker headers to fit the engine compartment and created the 2-1/2-inch Magnaflow-muffed exhaust system from mandrel bends. To make the car more serviceable Benchmark assembled the major components with stainless band clamps.