How the racing slick was born

By Ben Mozart Photography courtesy of Jim White When Tom “the Mongoose” McEwen, now 76, speaks of racing you are often struck by his power of recall and his perceptiveness, which is never more apparent than when he gets on the subject of race tire development. “The only reason we have tread on a tire,” says McEwen, “is to allow us to drive in the rain. As drag racing isn’t conducted in the rain, we would put our tires in a lathe in the early days, back in the 1950s, and we’d cut off the tread in an effort to put more rubber on the track.” Though shaving off the tread gave the early racers greater contact area it also created a problem: the rubber between the bottom of the treads and the top of the cords wasn’t always consistent. Invariably it was much too hard. Then in the mid-nineteen-fifties, a company called Bite by Bruce who produced recap tires in Arizona for road vehicles and represented by a most menacing logo, introduced the first tire with a slick surface. According to “Mongoose” McEwen, these recaps represented the origins of the modern racing slick tire. Before Burn-outs “In the old days before the practice of burnouts,” McEwen recalled, “when the cars approached the starting line, mechanics would soak rags in gasoline and wipe them around the circumference of the slicks in an attempt to soften the rubber and thus make the tire grip better.” Then in 1957 in Watertown, Massachusetts, Marvin Rifchin with his father Harry of M&H introduced the first dedicated racing slicks. Initially these offered less than...
How to make a Street Stock racing clutch survive

How to make a Street Stock racing clutch survive

By Freddie Heaney. Courtesy of Speedway Illustrated, Photos by Moore Good Ink: Racers frequently face the inconvenient fact that some clutch-flywheel assemblies are so light they fail prematurely, often during the taxing process of getting the car into the trailer. Curiously, most professional clutch makers agree that you quickly reach a point where the ultra light clutch unit has no advantage at all and instead its arch attribute, lightness, undermines the process bringing decreased durability. A stroke of marketing brilliance some might say! Racer purchases ultra light clutch, racer quickly destroys ultra light clutch, racer purchases successive ultra light clutch. You may think racers would resent these dubious practices, but there is no evidence to suggest they do. In all likelihood if you added a little strength to the unit you would probably gain 50 percent greater clutch longevity without any perceptible loss in power. In either case, to reduce these often unnecessary costs here are a few tips intended to prolong the life of the racing clutch.  Read Speedway Illustrated’s story...
Torsional vibes break crankshafts!  How could you identify them and, if necessary, eradicate them?

Torsional vibes break crankshafts! How could you identify them and, if necessary, eradicate them?

By: Bertie Scott Brown:  Harmonic balancers dampen torsional crankshaft vibrations and they perform their function adequately on common engines. But if changes are made to the engine, particularly to a racing engine, harmony might be lost. For example, if engine speeds at full throttle are significantly increased, the harmonic balancer could become out of tune. How would you ascertain if threatening torsional vibrations have accompanied the higher revs and how would you measure them? If necessary, how would you eradicate them? This problem is particularly acute on historic and vintage race engines where engine speeds have inevitably increased over time, yet often no provision was made for the harmonic balancer on the original engine. Earlier this year Virkler & Bartlett, (V&B) the Virginia race engine shop and hard-core problem solvers were invited to analyze potential crankshaft torsional vibrations in a vintage Maserati racing engine. Their calculations anticipated significant fourth order torsional peaks at 7,600rpm and smaller, fifth order peaks at 6,200rpm. What are fourth and fifth order torsional peaks? Camshafts and crankshafts vibrate torsionally (in twist) in the running engine. Camshafts are affected by the forces related to the opening and closing of the valves; crankshafts by the combustion events. As a result twisting deflection occurs in both shafts. Two of the many terms used to define torsional vibration are Frequency and Order. Frequency refers to how many things occur in a period of time; Order by the number of events per crankshaft revolution. If, for example, a rotating shaft is disturbed by two of these vibrations or resonances each revolution, they are defined as second order and they...
First power steering tester reveals more than you might wish to know

First power steering tester reveals more than you might wish to know

By Titus Bloom It’s common knowledge that the entry of one foreign particle in the power steering system can damage the pump. Even if the pump survives the ordeal the refuse will momentarily zap engine power each time it passes through the rotor housing easily consuming 10hp, according to KRC’s new and unique steering pump tester. “This custom-made machine records horsepower, flow and pressure and checks the data every 1,000rpm from 1,000 to 10,000rpm,” says KRC chief Ken Roper. “It even produces graphs and retrieves information we didn’t request! But perhaps its most valuable attribute is that it reveals information we never knew before, like power consumption under load, and it validates everything.” Though the average Sportsman race team may not be too concerned if a steering pump consumes 3hp or 6hp, others like NASCAR teams cannot afford any power-robbing deficiencies and would eagerly welcome even a ½ hp advantage. What caused recent power steering system failures? Recently new short track oval race chassis have suffered a spate of power steering failures. The troubles were traced to the pressure relief valve (spool valve) in the power steering pump. Apparently, galling had caused it to jam in the bore. “For years,” says Roper, “production road car pumps have been modified and offered for use on new race car chassis. As you’d expect, they are inexpensive and most of the time they perform adequately. But they have always been a marginal proposition for race cars as most of their internals are uncoated. Without exception, any friction in the pressure relief valve area slows steering response.” To maintain the valve’s proper function...
Minimizing spark scatter in the Vintage race engine

Minimizing spark scatter in the Vintage race engine

By Sam Logan Photography by Moore Good Ink & V&B Engines Often Vintage racing engines exhibit excessive spark scatter caused by torsional vibration in the distributor drive system. To correct it Virkler & Bartlett adds a miniature flywheel to the system. They mold a series of rubber couplers with a range of Shore A hardness, which allows them to tune the system. Note rubber coupler glued within steel ring.       How to get the best from a Vintage engine ignition system Chatham, Virginia:Vintage racers are often forced to live with points-and-coil ignition. But the most successful know the shortcomings of the ignition system and have it corrected. For the past forty years or so electronic ignition has been the standard, but most Historic race cars produced before the 1970s are equipped with something other. Unfailingly, coil-and-points ignition systems work best when optimized mechanically and electrically. But how is it achieved? Vintage racers seem to run a little faster each year, and as compression ratios and engine speeds creep up, deficiencies in points-and-coil ignition systems can precipitate the perfect storm of performance problems. Background Just over one hundred years ago, the brilliant engineer Charles Kettering invented the ubiquitous battery-powered “points-and-coil” ignition system that first appeared on the 1910 Cadillac. Remarkably, it was used in most cars until the mid-1970s. An engine-driven mechanical cam operated a set of breaker points, switching electrical current to the coil which converted it to high voltage required to fire spark plugs. A rotor within the distributor routed high-voltage impulses to the correct spark plug. The condenser had the dual function of extending the...