Of the
many forms of competition that racing now enjoys, one common trait they all
demand is a high level of skill and knowledge by the men and women responsible
for building the high performance engines that power their vehicles. These
engines are very expensive by any measure, and to acquire maximum performance
one thing all engine builders soon understand is the importance of one group of
the engine's components, known as the VALVE TRAIN.
VALVE
TRAIN is the most temperamental and demanding category of an engine's design.
Most engine failures are the result of something breaking in the valve train,
usually a valve spring or rocker arm. But most improvements in engine
performance come from valve train development. The most precisely designed and
driving component of the valve train, which is aptly referred to as the "heart"
of the engine, is precision ground to tolerances less than 2/10 thousandths of an
inch (.0002"), and computer designed to tolerances 10 times greater. This
precision component works in harmony with three other components of the valve
train to open the valve, and determines
all of the critical timing for the engine's ability to breathe the greatest amount
of airflow, while venting wasted gases, all in an effort to produce maximum
horsepower. It is known as
the CAMSHAFT.
CAMSHAFTS of today's high performance OHV
(Over-Head-Valve) engine technology are the "heart" of a FIVE (5) component system
that makes up the valve train, which is arguably an antiquated principle of design, dating back nearly a century.
Aside from the last component in our list: the "VALVE," these other three components
are respectively known as the LIFTER (TAPPET, or CAM FOLLOWER), the PUSH-ROD and the ROCKER ARM.
ROCKER
ARMS are the FINAL LINK which operates the opening and closing of the ever
critical valve timing. What makes "rocker arms" so critical in design, which is
so ironic as to how long they've been ignored for this need, is that they are a
RADIAL instrument which CONVERTS
LINEAR information. In other words, they
operate around an axis of motion, to connect two critical components which are
essentially designed only for "in-line" motion. This simple observation is
critical in understanding, and believe it or not, these principles of linear to
radial conversion was NEVER explained or published
until Jim Miller illustrated it many years ago in numerous articles. If this "conversion" is not done accurately, then the success of the cam's performance and efficiency
is wasted. Rocker arms have been made in many forms for high performance use,
usually called a "roller tip" and
"needle bearing," most often from aluminum, as well as various steel
and more exotic metals such as titanium. Aluminum versions date back more than four (4) decades on cars. Aircraft radial engines
used "roller" rocker arms 30 years before this. Rocker arms are without
a doubt one of the most important -- most often chosen -- and most often changed
components of any serious engine builder seeking optimum performance from
their high performance engines, regardless of its destined use. For the inside
information, go to:
MID-LIFT TECH.
