Kia 2004.5 Spectra Service Technical Training page 67

2004.5 Spectra Technology
CONTINUOUSLY
VARIABLE VALVE
TIMING (CVVT)
CVVT AND NON-CVVT
SYSTEM COMPARISON
Powertrain
Depending upon engine RPM and load, CVVT system
varies the intake valve timing 40 degrees of cam
angle, and the intake valve timing is optimized. When
the shown intake valve angle "bell" is moved to the
right side, the intake is in Full Retard and Full Advance
when the "bell" is on the Left Side. The exhaust valve
angle remains constant as shown.
This chart compares camshaft timing of the 2.0L Beta
engine without CVVT (not available on Kia vehicles
sold in the U.S.) and with CVVT. At 12 o'clock on the
diagram is TDC, while 6 o'clock is BDC of the piston.
The camshafts rotate clockwise.
The valve timing does not vary on the exhaust
camshafts, which is shown in the right column.
• At 6 o'clock (bottom) the exhaust valve starts to
open 50 degrees before BDC (42 degree in CVVT)
• The valve closes at 6 degrees after the piston
reaches TDC.
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