The following tables provided by COMP Cams illustrate how variations in lobe separation angle and cam timing affect engine behavior. Engine builders can refer to these characteristics often to determine the likely effect of any cam timing alterations they may contemplate. Knowing how these things affect engine operation can help you in the engine planning stages if you want to leave some tuning leeway in your cam selection. Our thanks to Comp Cams for providing this easy to use reference guide for our readers.

EFFECTS OF ALTERING CAMSHAFT TIMING Advancing Retarding Begins Intake Event Sooner Delays Intake Closing Event Opens Intake Valve Earlier Keeps Intake Valve Open Longer Builds More Low-End Torque Builds More High-RPM Power Decreases Piston-Intake Valve Clearance Increases Piston-Intake Valve Clearance Increases Piston-Exhaust Valve Clearance Decreases Piston-Exhaust Valve Clearance

EFFECTS OF CHANGING LOBE SEPERATION ANGLE (LSA) Tighten (smaller LSA number) Widen (larger LSA number) Moves Torque to Lower RPM Raise Torque to Higher RPM Increases Maximum Torque Reduces Maximum Torque Narrow Power band Broadens Power Band Builds Higher Cylinder Pressure Reduce Maximum Cylinder Pressure Increase Chance of Engine Knock Decrease Chance of Engine Knock Increase Cranking Compression Decrease Cranking Compression Increase Effective Compression Decrease Effective Compression Idle Vacuum is Reduced Idle Vacuum is Increased Idle Quality Suffers Idle Quality Improves Open Valve-Overlap Increases Open Valve-Overlap Decreases Closed Valve-Overlap Increases Closed Valve-Overlap Decreases Natural EGR Effect Increases Natural EGR Effect is Reduced Decreases Piston-to-Valve Clearance Increases Piston-to-Valve Clearance

CAMSHAFT GEOGRAPHY AND LOBE FUNCTION 1) Max Lift or Nose 2) Flank 3) Opening Clearance Ramp 4) Closing Clearance Ramp 5) Base Circle 6) Exhaust Opening Timing Figure 7) Exhaust Closing Timing Figure 8) Intake Opening Timing Figure 9) Intake Closing Timing Figure 10) Intake to Exhaust Lobe Separation