In many areas of motorsport, components are pushed to their limit to squeeze out as much performance as possible. Finding that balance between more performance and too high a risk of failure is something that engine builders are constantly wrestling with. Ron Shaver of Shaver Engine Specialties, in Torrance, California, builds Tony Stewart's World of Outlaws 410 cu in sprint engines. And, like many other parts of his engines, valve springs are a vital area where risk and reward have to...
The poppet valve is almost universally used in all forms of transport powered by an internal combustion engine. Motorsport has always had a buoyant two-stroke sector in the motorcycle arena, although this is on the wane now with Grand Prix motorcycle racing having bidden farewell to its last two-stroke class at the end of 2011. So, we have confined ourselves to a four-stroke future, and this generally means poppet valves. Brave attempts by forward-thinking engineers over the generations to...
In the previous article on rocker stands, and as a general theme to the subject of pushrod valvetrains, the importance of stiffness was stressed. Also important though is that the mechanism is set up on the engine as intended when designed. This means that the relationship between the tip of the valve, the roller tip and rocker pivot are as designed. Not only does a badly set-up mechanism deviate away from the designed valve lift profile, but the relationship of the contact between the...
Finding the right valve springs for an inline four-cylinder USAC National Midget engine that makes upwards of 365 hp at the wheels could be a difficult procedure. But, says Erik Milholland, manager of the racing division at Kentucky-based Stanton Racing, "In the last couple of years we've found some really good springs." Stanton Racing fields both Mopar and Toyota Midgets in USAC competition. The company took over the build and rebuild procedures for California-based Toyota...
The question of valve material selection has been discussed before in the RET-Monitor. Much of the motivation for a given selection is provided by the operating conditions in which the valve must operate. Some materials are not suited for very high temperature use while others are too dense to be used in conjunction with very extreme valve lift profiles. In previous articles, we have looked mainly at the different classes of material with a view to having the valves made in a certain...