Most
of the advanced
and leading edge "innovation" in rocker arm valve-train was not
accomplished by any of the "big names." Instead, the most fundamental concepts
for "efficient" rocker arm geometry went undiscovered for many years, which
allowed significant cam information being lost with excessive in-and-out motion, until MID-LIFT
was developed for an engine few people cared about; the BOSS 429.
Jim Miller
developed MID-LIFT in 1973, and Patented the concept in 1982. For many years the
top name valve train companies tried to ignore it. Some denounced it.
Eventually, some copied it (poorly). However,
since 1992, it is the only method recommended by Chevrolet's Racing
group; and since 1999 it is the only geometry mandated by Chrysler's performance engineers.