 The "infinitely variable" portion of the A-VTEC is what makes it stand out as a serious evolutionary step in the world of VTEC.Advanced VTEC has a standard camshaft and rocker arms, attached as they normally are with camshaft overhead, and rocker arms pushing down on the poppet valves.The camshaft is surrounded by a partially open drum which has secondary rocker arms attached to it via a pivoting point.