Arch rule of carburetor tuning: Ignition first

Arch rule of carburetor tuning: Ignition first

By Sam Logan. Photographs by Moore Good Ink:  Download text and hi-res images here. The cardinal rule of carburetor tuning is Ignition First. Once the static ignition setting and the ignition advancing mechanism in the distributor is correct, the air-fuel mixture can be tuned for full power and fuel efficiency. High-performance carburetors, intake manifolds, cylinder heads, camshafts, and other tuning components are all dependent upon correct ignition timing; if the spark is not delivered at the proper time to the combustion chamber, the quest for optimum power or economy is impaired. But the distributor has vanished! Tuning contemporary hot rods involves electronics and computer software. Sensors abound. They sense Manifold Absolute Pressure, Mass Air Flow, crankshaft position and so on. They report to an ECU (engine control unit) that constantly ascertains all the variables and tells each spark plug when to fire. Where there was once a distributor, multiple coils now exist, often one on each spark plug. Still, what a joy it is to understand the psychology of the hot rodder who lusts for a carburetor and a distributor. And, ironically, older vehicles can be simpler to tune. They require no fancy equipment or computer knowledge, often just a timing light, a screwdriver and a few wrenches. Brief background on points-and-coil ignition Before sophisticated electronic management systems arrived, we used the points-and-coil ignition system that first appeared on the 1910 Cadillac. A distributor was employed to determine when each spark plug should fire. An engine-driven mechanical cam in the distributor rotating at camshaft speed operated a set of breaker points. The points switched electrical current to the coil which converted it...
Inadequate ignition timing:

Inadequate ignition timing:

The carb tuner’s most intractable problem By Sam Logan Photographs by Moore Good Ink   Ask Demon Carburetion of the greatest obstacle in tuning hot rod carburetors and they’ll tell you ignition timing. Highly tuned engines, those with high-performance camshafts, cylinder heads, and intake manifolds often exhibit a lazy response or, worse, hesitate under acceleration or die at idle. Interestingly, these perennial troubles are invariably resolved by increasing the initial or static ignition timing. This is achieved simply by loosening the distributor clamp and slightly rotating the distributor body. Consequently, either the points or an electronic pickup will be triggered earlier. This sends the current directly to the coil or to an electronic ignition box. The high voltage current then returns to the center of the distributor cap, making direct contact with the rotor. As the rotor spins the current jumps across the tiny gap to each of the small metal tabs, completing the electrical circuit and sending short–duration, high voltage currents to each spark plug on time. However, to increase the static timing also increases the engine’s progressive timing; that is, its total timing which is impelled by mechanical advance mechanisms or vacuum advance or both. Lazy response eradicated by increased static timing and decreased progressive timing Let’s say the engine operates at its optimum when its initial or static timing is advanced to fire at 18 degrees before the piston reaches Top Dead Center. Let’s further assume the distributor’s progressive advancing mechanism will deliver an additional 24 degrees, resulting in total ignition timing of 42 degrees—which is excessive for most hot rod engines. Generally high-performance small-block and...

Snake and Mongoose movie

A true story that inspired a movie By Archie Bosman Pictures by NHRA The Los Angeles premiere of the Snake & Mongoose movie brought a fine sense of occasion to the racing world on Monday evening, August 26. The new movie tells the tale of two of drag racing’s most illustrious drivers Don “Snake” Prudhomme and Tom “Mongoose” McEwen. Held at the Egyptian theater on Hollywood Boulevard, Hollywood—the venue for the movie industry’s first premiere in the early nineteen-twenties—invited guests began arriving at 4pm. By around 5:30 over 500 had gathered, including movie and racing celebrities, at which time they began their walk along the red carpet toward the theatre. “We’d move a couple of paces then stop,” said McEwen, “I estimated there were 100 photojournalists taking pictures and conducting interviews, including the New York Times. It was an impressive affair—a much bigger event than I had expected. The place was packed and I was honored to feel part of it all.” Earlier at 11am the first showing was reserved for the film-maker’s production people, which was followed by another performance at 2pm for the world’s press. Afterward, they were invited to Sadies, a private night club adjacent to the theatre where they feasted on sumptuous cuisine at a $50,000 party with three or four open bars. Reveling in the warmest hospitality, “it was a high-class affair,” declared McEwen. Most memorable victory in 60 years of drag racing history In creating the movie narrative, former editor and racing writer Alan Paradise had devoted eight months to writing the script and a further four months to completing the re-writes. His work...
The racer and his infatuation with noise:

The racer and his infatuation with noise:

Blaring exhausts make hooligans of all. By Freddie Heaney Images by Moore Good Ink In all likelihood every U.S. road race track has received reams of complaints about excessive noise. Two years ago in England, Mallory Park’s very existence was threatened by the blight. It is the most malignant force currently facing our racetracks and the new spirit of our age, Track Days, has exacerbated it. When we were young, acquiring a noisy muffler was a priority. We were 19 and needed to be noticed urgently—what was wrong with that? The smart ones among us, though, knew that the way to speed was via stealth. Of course racers don’t have a monopoly on noise. Just attend any rock concert and the middle-aged will be standing there with ear plugs forced firmly in place. Even a half-wit observing this strange custom would sense the absurdity of it all. And more significantly still, most complainants, like those residents of every village surrounding Mallory Park, have no desire to see their local circuits closed. They just ask the enthusiasts to enjoy themselves while showing a little more consideration for others. The amiable answer To this end V&B provides a solution. They understand noise requirements and they know how to meet them with lightweight, finely crafted mufflers. These new silencing systems feature inner bulkheads and other devices that can be quickly adapted to suppress noise to the levels required. For more information contact: Virkler & Bartlett Chatham, Virginia (434) 432-4409 rgbartlett@vbengines.com www.vbengines.com...