BACKGROUND

THE HISTORY of traditional rocker arm geometry, for those who've used any philosophy of design at all, was always based on two things: a SHOE TIP (scuff pad) contact surface for depressing upon the valve, and a formula for roughly measuring the rocker arm's length and pivot position, and referred to as the 1/3 RULE. Roller tip rocker arms were not novel to Over-Head Valve (OHV) engines when they were first applied to V8 automotive engines in the 1950's, having been used on radial aircraft engines decades before. But roller tip rocker arms DID make the LEAP FROM the SHOE tip principles of design. THIS was a mistake.

In 1958, the first roller tip aluminum rocker arms were developed from an inaccurate method of design that wasted rocker arm motion. It has been duplicated by every popular rocker arm manufacturer ever since. It doesn't matter how big the name, or how long they've been around, even the OEM manufacturers didn't follow the now accepted (and demanded by some Detroit companies) geometry called MID-LIFT.

The History Of MID-LIFT explains how an amiable, hard working, easy going Midwest machinist made a simple mistake by taking an idea in his head to cut and paste a roller to the end of a shoe tip rocker arm. But how do you explain the insanity of bad geometry being used by racing's valve train industry for so many years? The "roots" of most of racing's oldest and most respected companies lies in men of racing passion, who got their hands dirty; not in squeaky clean white lab suit  engineers sitting at a draft table holding a slide rule. The answer is underscored by examples set in Detroit. There is no lack of accredited engineers at Chevrolet, Chrysler or Ford. Yet, for cost reasons or just adhering to old school thinking mistakes continued.

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