Pro Street 1970 Pontiac GTO - Gleaming Tower Of Power

Owner Bill Bolin tells HPP, "I like my 1970 GTO because it stands out in a crowd of other Pontiacs and Pro Street cars." This is possibly the understatement of the year. With two blowers stacked one on top of the other, huge-by-large rear meats, and a hallucination-inducing hue, this GTO attracts curiosity seekers like children to an ice cream truck. The buzz on the Internet was intense before the Pontiac was even complete.

Bill and his wife, Christine, aren't strangers to Pro Street Pontiacs, having built a '68 Firebird from 2001 to 2003. In fact, it was while searching for parts for his Firebird that he found the GTO on an online auction four years ago. "It was originally built into a Pro Street car from 1987 to 1989," the resident of Shady Side, Maryland, recalls. "The previous owner drove it until 1991 and then parked it in a barn for 12 years, which took its toll."

When Bill purchased the GTO, it had a 406 Pontiac with a BDS Stage-2 6-71 blower and an Enderle Bug Catcher up top. After applying a few Band-Aids to get it on the road, the Bolins cruised in the GTO during the summer of 2003, but Bill saw the mechanical handwriting on the wall and decided to redo the Goat for the following show season. What better place to begin than with the powerplant?

The Builup

Bill retained the BDS Stage 2 blower and built this 455-based, 474-cubed powerplant in 2004. All the machine work was performed by Precision Engine Machine in Hyattsville, Maryland, and Bill worked out the combination and assembled the engine himself.

Atop the Tower of Power are a pair of Holley 750 supercharger carbs, which are boost-referenced, and beneath them is a modified Offy 2x4 intake manifold. A set of 124cc-chamber 6H heads ensure a 7.7:1 compression ratio when combined with the 4.180 bore, zero piston-to-deck height using the 0.060 Ross-forged flat-top blower slugs, and the compressed thickness of the Fel-Pro head gasket at 0.041 inch.

Bill bolted a 4.250-inch stroker crank, which swings Scat forged rods with upgraded rod bolts to handle the cylinder pressure, into the four-bolt main stud girdle and Butler lifter-bore, brace-equipped 455 block. Oiling is provided by a blueprinted Melling pump working from a Canton pan to cool the Clevite 77 bearings. For oil control in the cylinders, Bill chose Speed Pro piston rings.

A solid-roller cam bumps the Ferrea SS 2.11/1.77 valves in the owner-ported heads (five-angle valve job, 230-cfm intake flow at 28 inches of pressure at 0.600) via Harland Sharp 1.50:1 roller rockers and Comp Cams valvesprings and pushrods. The big Comp Cam features 268/276 degrees duration at 0.050 and 0.609/0.609 lift. It was designed as a blower cam with a wide 114-degree LSA, resulting in less overlap to retain cylinder pressure and increase torque. The cam was installed straight up and has a centerline of 114 degrees.

An MSD Pro-Billet distributor makes the spark and is augmented with a Blaster 2 coil, boost retard, Taylor wires, and Autolite 26 plugs. Total timing is set to 32 degrees all-in at 3,000 rpm.

Though it may seem that Barry Grant's 280-gph fuel pump is too small for the combo, Bill tells HPP that advice from the pros says otherwise. The remainder of the fuel system is comprised of a -10 line from the fuel cell to the Holley big-port regulator (set to 6.5 psi) and a pair of -6 lines from the regulator to the carbs.

A set of 2-inch primary headers, made by Ralph Hardesty at Superior Automotive in Bowie, Maryland, were mounted using Hedman adaptors to fit the big primaries to the D-port heads. These headers feature 3.5-inch collectors and dump into a 3.5-inch exhaust system with Pypes Violator mufflers, custom 3-inch tails, and stock-appearing splitters.

Bill also installed an elaborate intercooling system using an air-to-water Super Chiller intercooler under the blower, which is fed cool water from a 10-gallon aluminum tank mounted between the wheeltubs inside the Pontiac. The system uses a Jabsco pump to circulate water from the tank through a separate radiator mounted up front, after which it's run through the intercooler and returned to the tank.

While the engine build was in process, Bill went through the entire suspension system, replacing many of its parts. Attached to the 2x3, boxed, mild-steel frame is a rack-and-pinion steering system; GM spindles; tubular control arms; and Afco coilovers with 400-pound springs. Cross-drilled 12-inch Aerospace Components rotors and GM single-piston calipers comprise the front brakes.

Moving rearward, we find a chrome-moly cage that not only protects the occupants, but is also an integral part of the chassis, creating a more rigid structure. As one would imagine, the rear features custom wheeltubs in the Pro Street tradition, and Bill installed a narrowed 9-inch Ford fitted with 4.11 gears, Strange 35-spline axles, 11-inch drum brakes, and a CE ladder-bar suspension with double-adjustable Koni coilovers. He also replaced the electrical and cooling systems before hitting the 2004 summer cruises and shows.

The following winter, the GTO was torn down again and treated to a new interior, gauges, wheels (15x4 and 15x14 Weld Dragstar), tires (M/T 26x7.50x15 / ET Street 33x18.5x15), and an NOS show-blower polished stainless nitrous system that is adjustable for up to a 300hp shot. Also installed at this time was an ATI 9-inch converter with a 4,200-stall speed as well as a Lightning Rod-shifted Turbo 400 that was built to the hilt by Thoroughbred Trans in Laurel, Maryland and sports a reverse manual valvebody, transbrake, and B&M cooler.

To ensure the torque makes it to the rear, a set of 1350-series U-joints were mated to a custom driveshaft.