This integral two-stage fuel regulator valve uses low pressure, low flow in "cruise" mode
Even in this day of increasingly sophisticated electronic fuel control systems, carburetors are still often the component of choice for racers and high-performance street machine enthusiasts alike. And why not? Over the course of the past 200 years or so, carburetor technology has evolved and improved by leaps and bounds. Carbs are a known quantity, and they work. But even after all this time, there are still aspects of carburetor function and performance that are hard to control, which means there are still problems to be solved.
An ultra-high-performance engine, whether in a NASCAR, a Pro Stocker, or even a heavy-duty street machine, needs an incredible amount of fuel to do what it's supposed to do at high speeds. Unfortunately, that can leave you with a fuel meter whose float bowls flood at low speeds. And even if you use high pressure to get the fuel to the carburetor, it may not actually get in to the carburetor, thanks to the foaming and float bounce that high pressure can cause. "Everybody's got enough fuel pressure," says veteran carb tuner Dave Lange. "We just couldn't get enough into the float bowls."
Lange, who through the years has worked on everything from Stock Eliminators to Blown Alcohol cars and now works out of his own shop, Fuel Curve West, has fought these problems for years and recently came up with a solution: this integral two-stage fuel regulator valve. Lange invited us over to check out his invention and even explained how it works. The valve mounts to the carburetor like any other similar piece and also works like one at low speeds. An adjustable internal regulator runs around 1 to 2 1/2 psi of fuel pressure, which is ideal for, as Lange puts it, "puttin' around the pits, staging, and driving in cruise mode."
The Fuel Curve west regulator is laid out as follows: fuel flows in (A) and out (B), as us
The regulator also features a solenoid-activated "high side," which can be triggered in a number of ways, such as a carb-mounted micro switch, an MSD-style rpm-activated switch, or even a "chipped" ignition port. Once activated, an internal diaphragm opens, allowing fuel to flow unrestricted through four orifices. At its top setting, 9 psi, Lange's valve will flow a staggering 2,600 pounds per hour (for reference, a Lear jet flows 2,180 pph). The normal pressure setting is between 4 and 6 psi; over 6 pounds, the foaming and float bounce problems return. At 3-6 pounds of pressure, however, Lange tells us that foaming is "about 70 percent gone," while still flowing 4 gallons a minute through the needles and seats. Lange even includes a set of .150 needles with each regulator. While needles this large might be hard to control with a high-pressure system, Lange tells us his high-volume, low-pressure system will "keep 'em fed without a problem."
Lange summed things up very succinctly, so we'll let him speak for himself: "You essentially have a two-stage system, so that you can have the comfort of not flooding while you're cruising. You go to the 'high' side, you've got enough fuel to feed anything." So far, most of Lange's feedback on his regulator has come from Pro Stock and Pro Stock Truck racers. Even on "real comp stuff" like these guys run, he tells us, "we only run 4-5 pounds of pressure. We don't need more, 'cause we've got a whole bunch of volume."
Of course, the first question out of the mouths of many is, "Will it help me go any faster?" The answer is, it certainly might. Lange didn't design his regulator with that in mind; he was only interested in controlling the fuel flow problems. But, given that this system allows a high volume of unaerated fuel to get into the carb, it's not surprising that the early results on performance enhancement are encouraging. One of the first shops to get one of Lange's regulators, ironically enough, was Vrbancic Bros. Racing (1463 E. Philadelphia, Dept. SC, Ontario, CA; 909/930-9980), a "competitor" of Lange's own Fuel Curve West. According to Lange, the brothers "didn't believe you could feed an engine on 4 psi; they made 1,040 horsepower with a 540ci engine running one four-barrel carb and 4 psi. They were very happy." We bet!