"It ain't a hot rod until it's got a bunch of louvers in it," or so says Editor Brian Brennan. He should know; Hot Rods by Dean recently built him a sharp A-bone on Deuce 'rails, and even though many say it's Brian's finest car, one thing prevented it from being his finest hot rod: louvers. While the car kept cool and technically it looked great without them, it just didn't look right.
The link between louvers and performance, while indirect, is strong. When fan and cooling technology was low, automobile manufacturers cut holes in the engine's compartment to relieve it of the engine's waste heat. Louvers became the preferred hole since they required simple tooling, imparted a sort of visual element, and somewhat protected the engine from damaging elements like water, dust, thieves, and the kid next door.
As engine power grew, so did the waste heat the engine generated and the need to evacuate that much more heat from the engine bay. As a result, louvers became a layman's means to evaluate a car's performance: More louvers must mean more power, right? Just look at a Model J Duesenberg or an Auburn boattail speedster; there's practically more hole than hood on the things, and they're fast bastards.
Hot rodders, specifically those after World War II, immediately picked up on the louver practice, as they often crammed the largest engine capable of generating the most heat-like a V-8 Ford, Olds, or Cadillac-into the smallest cars with the least means to shirk that heat. Eventually, lakes and drag racers, citing the Law of More (more means better), started ventilating more than just engine compartments; trunk lids, roofskins, and every other low-crown sheetmetal surface began to bear the mark of the local louver punch. Before you knew it, the kid with the hand-me-down Plymouth sedan showed up to the burger stand with a split manifold and louvered hood in a bid to win something-even if only the appeal of the opposite sex.
And half a century on, we're still stuck on louvers.
Luckily the louver is easy to implement, even if it's somewhat tough to master. Louver dies aren't much more than a cross between a paper punch and your dad's handheld book embosser in that they simultaneously form and slice sheetmetal. They differ from the handheld units in the fact that they require pressure like that generated by a mechanical punch or hydraulic press to form their shape in metal.
If louvers have a downside, it's availability; not many more companies offer louver dies today as they did in the past. Mittler Bros., Van Sant Enterprises, and Fournier Enterprises all carry Mittler Bros. 1- to 5-inch die sets and hydraulically operated kits; however, many of the noted louver pressers like Stan Betz and Eric Vaughn (who admittedly based his on Art Ingels', of Kurtis Kraft fame, dies), made their own from tool steel and tubing. According to Betz, "There was never all that much demand for louver dies. After all, one guy with some dies could cover an area like Orange County." Williams Lowbuck Tools makes a handy set of dies that transform a bead roller into a louver machine that will form straight or curved louvers in any length, but they depart so radically from the punch style that we will address them in another story.
If you're not into buying or making your own dies, or even punching your own louvers for that matter, consider commissioning Dean Livermore, Eric Vaughn, or a third resource, Sir Michaels, to punch the holes in your project. While Eric and Dean's louvers follow a more traditional louver shape, Sir Michaels offers a vast array of louver styles-probably one of the most comprehensive in the country. Since Dean, the guy who built Brian's car in the first place, owns a louver press of his own, Brian's decision came naturally.
Whether you elect to do it yourself or farm it out, and regardless of what style you prefer, always keep the following in mind: You can build a custom car or a smoothie street rod, but until it's riddled with louvers, it'll never be a hot rod. Just ask Brian Brennan. He'll tell you.
Give two people access to...
Give two people access to a louver press, and it's pretty much guaranteed that no two sets of louvers will look alike. Not coincidentally, the shape of the louver is just as important as the pattern. Dies from the past typically pressed softer, more curved louvers that look just right on traditional cars. As years passed, louvers grew sharper and more angular. Even though the clamshell-shaped louvers lend themselves to traditional cars, they're timeless; they look just as comfortable on contemporary cars.
Since Dean punched louvers...
Since Dean punched louvers in a blank sheet, he incorporated the louver positions with the hood's dimensions. You may want to plot additional lines to illustrate the louvers' widths and individual positions to get a better idea of how the finished product will work.
The louver dies themselves...
The louver dies themselves are relatively simple. As the male die pushes its way into the female die, the close tolerances between each die's straight edges initially shears the metal. Once the dies pass the shearing stage, the male die continues to stretch or "upset" the metal into the louver shape. Also note the pins on the yonder side of the cap screws.
Punching a louver naturally...
Punching a louver naturally creates a straight edge that stands proud from the metal panel. That's where the pins come in. If Dean orients the prior louver's straight trailing edge (cut edge) with those pins, he's assured consistent spacing between his louvers, in this case 1 1/4 inches.
Dean can increase the gap...
Dean can increase the gap between louvers by dropping bushings over the pins, or reduce the gap by eliminating the pins altogether. Gap withstanding, however, he still needs to align the panel's layout lines with those on the louver dies if he expects the louvers to line up straight.
For consistent lateral position...
For consistent lateral position along each louver row, Dean built a fence, like those found on table saws. Once he sets up the fence, all he has to do is position the panel against the fence and reposition each louver's leading edge on the pins.
To get additional rows, Dean...
To get additional rows, Dean merely realigns the fence and punches away. It goes without saying that this sort of fence construction works only with flat panels like this hood side. Punch an F-100 hood, for example, and you're stuck with layout lines and good hand-eye coordination.
Pardon our pun, but a few...
Pardon our pun, but a few louvers punched into Brian's roadster's hood sides really gave the car a bit more punch. The missing louver has a story behind it too. First, it's a nod to Jim Khougaz's channeled Deuce roadster; legend has it that someone distracted the louver presser and he resumed his duties exactly one louver off. In this case, this missing louver would've been the 29th on the car, which is not so coincidentally the year of the car. Get it?
If you'd love to be the go-to...
If you'd love to be the go-to source for louvers in your area, consider Mittler Bros. louver press. It punches 1- to 5-inch louvers in most aluminum sheet or in up to 16-gauge steel. The kits include a 10-ton hydraulic ram, a precision slide assembly, and a set of your choice of louver dies. It also includes blueprints and complete instructions for how to build a 48-inch-throat-depth press.