The Weber Mystique

by Rick Kopec (7/10/08)

Just what is it about these carburetors that make grown men weak at the knees when they look under an open hood and see a brace of them sitting on top of an engine? Two rows of stacks topping these intricately sculptured symmetrical pieces of pot metal, standing at attention, their formation marching back into the dark recesses of the engine compartment. Separate fuel lines snake around to bring the go-juice where it is needed. Even at rest they seem ready to spring to life and spur unthinkable amounts of horsepower out of the engine sitting below them.

Cobra engineIt probably all began when the first Cobra was created in Dean Moon’s shop in Santa Fe Springs, California in 1961. A 260 cubic-inch small block Ford V8 went into CSX2000, topped by a 4-barrel carburetor. But before too long, they were gilding the lily. Another engine was substituted; this one was a high performance version and in a go-for-broke move to maximize the impact (and to provide added under-the-hood punch) a set of four Weber 48 IDM side-draft carburetors were employed, on a manifold that was specially fabricated in Dean Moon’s shop. Oh yeah, Dean was a Weber dealer and he was in on the ground floor. These carbs were just starting to show up on Chevy small blocks that powered lakesters and modified sports cars. They hadn’t spread to the street rod world just yet. European racecars had been using Webers for years, and they were practically a signature on Ferrari engines. When Cobras began racing, it was only natural that this set up was used. Webers became the standard for small block competition engines, employing a downdraft intake developed by Phil Remington. A typical Cobra race engine yielded upwards of 385 horsepower on Shelby American’s dynamometer.

Although a Weber set-up itself is essentially a bolt-on, there is a lot more to it than that. One of the benefits of Weber carburetors is that they are infinitely tunable. With a typical Holley 4-barrel, you can change the jets and fiddle with the idle screws to get the engine running evenly. The float levels need to be right and the linkage should operate smoothly but if everything is working right the engine should be turn-key and trouble-free. But with Webers, “infinitely tunable” is a double-edged sword. There are a lot of components that can be adjusted or changed: main jets, idle jets, jet carriers, needles and seats, air correctors, chokes, emulsion tubes and secondary venturis. Of course, with four carburetors—and each with two barrels—that means that you multiply everything by eight. Sometimes when you make one change, it affects other things (the oft-described “Make It Worse” scenario). This can lead to Weber-dementia, which often results in hasty removal of the entire system and selling it to the first person who comes along and makes an offer, no matter how low-ball it is.

Daytona Coupe engineIn 9 out of 10 cases, the new owner, astounded by his unbelievably good fortune in finding a complete Weber set-up for a bargain basement price, doesn’t want to waste a minute asking the seller why, exactly, he is letting them go in the first place. He doesn’t want provide an opportunity for seller’s remorse. All he can think of is whisking his new Weber set-up home and setting them on his workbench where he can dream about the surprise and envy that his open hood will produce. This is the stuff dreams are made out of.

It is also the stuff of nightmares, because if the new owner is trying to figure out how the system works on his own, unless he is very lucky or very well versed in the concept of a fuel delivery system, he is heading for the painful reality that, like root canal, brain surgery or a clogged septic system, Weber carburetors are something best left to a professional. “Don’t try this at home” definitely applies. When Webers function perfectly they are like a beautiful symphony. But when they do not you’ll be thinking you’re the Bill Murray character in “Groundhog Day.” You get in your car with a screwdriver, and you can’t drive five miles without stopping to make “just one more adjustment.” And no matter what you do, they still pop, snort, spit, cough or stall. And that’s if you’re lucky. Because the worst-case scenario is an explosive backfire, followed by the underside of your hood being scorched. You have a fiberglass hood scoop? It’s going to look like the ashtray you made in 5th grade art class when the kiln exploded.

Shelby engineThe best advice you can get is to “seek professional help.” But keep in mind that Weber specialists aren’t as plentiful as Starbucks. A little homework is required. Whenever you see a car with Webers, ask the owner who set them up or tuned them. Is he or she happy with their work? When you start hearing the same name more than a few times, you may have discovered the answer to your problem. Getting a Weber system to function properly is not impossible. It is not a fruitless search for the Holy Grail. But it requires patience, optimism and, oh yes—money. You’re paying someone by the hour, and the first thing they try may not be the thing that works.

Eventually your Webers will sing to you and you’re going to love that song. When 6S118 had a 4-barrel, it was possible to squeeze 18 MPG out of it if I drove like an old lady. Once I put Webers on it the mileage immediately dropped to 9 MPG because I never got tired of hearing that banshee wail. But I did get tired of stopping to fill up every 150 miles. The answer was simple: I fabricated a 32-gal. R-Model gas tank. So while that didn’t improve the mileage, it extended my driving range to 300 miles on a tankful—the same that I was getting with the 4-barrel. The only difference was now it costs twice as much to go the same distance. But the Webers make up for that minor inconvenience.

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