The following pictures shows Honda Accord VTEC engine diagram. The engine has a normal 4 valves per cylinder arrangement. At low end speed, the primary intake valve operates at normal lift while the secondary intake valve opens only slightly to prevent fuel accumulation in the intake port. At high engine speed the primary and secondary intake rocker arms are connected to the mid intake rocker arm to allow high valve lift. A synchronizing piston connects/disconnects the three intake rocker arms. Hydraulic pressure against a timing piston moves the synchronizing piston A and B one direction, while a stopper piston and return spring moves the synchronizing piston back when hydraulic pressure is reduced.
The above VTEC engine diagram shows following parts: primary rocker arm, camshaft, synchronizing piston A, synchronizing piston B, timing piston, intake valve, timing plate, mid rocker arm, and secondary rocker arm.