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Pump Gas Nailhead Build Takes Innovative Engineering Skill

The 1953-1964 Buick “Nailhead” V8 engine is a different kind of animal. These engines have a firing order that varies from that of most other GM V8s.

By John Gunnell

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The nailhead has more in common with a pair of four-cylinder engines than a V8. Like a four, the nailhead is a torquey motor, making all its torque at idle and then, as the rpms go up, the torque goes down and the horsepower rises.

Engine builder Guy Henson recently did a custom, high-tech build on a 401-cid Buick nailhead for a ’39 Ford Standard street rod. There aren’t many Ford Standard Tudor Sedans left today, so the owner of this unusual car wanted an equally unusual engine to power it. Henson built him an engine that he could cruise with after pulling up to a gas pump, filling the tank and driving away.

He rebuilt the bottom end, then started to think about his engine management choices. Since he already had a Whipple supercharger he planned around it. Henson hand-carved a billet intake manifold out of five different chunks of aluminum, put the Whipple on top, added a custom plenum and capped all this with eight Hillborn throttle bodies with spun aluminum velocity stacks and filters.

Ribs were carved into the intake that matched those in the supercharger. It looked nice, so Henson had it powder coated. He played Pinocchio with the Whipple, extending the nose piece four inches to get the belts to align.  Then, he carved a water pump pulley out of billet and put a crank sensor on it. Since the customer had air horns, Henson glued some 2 x 6-in. wood pieces together to mock up a plenum. He then laid it out and carved out half of it on his milling machine, then sent it off to be digitized and replicated via CNC machine.

Henson added an elbow on the back of the plenum to hide an IAC (Idle Air Control) motor in, so he can control the throttle blades. He can completely close them shut if he wants to, bringing the engine down to a nice purr at idle. The throttle bodies can be positioned at any point from straight out to a 30-degree angle, which allows different “looks” with the same equipment. Guy went for driveability over brute horsepower. The car owner can hit the button and get instant starting. The engine makes 20 in. of vacuum at idle and when it comes up it has eight pounds of boost with the Whipple supercharger operating.