Effects Of Changes In Cam Timing And Lobe Separation Angle

Author: Comp Cams

The following tables illustrate how variations in lobe separation angle and cam
timing will effect the behavior of the engine in which the camshaft is installed.

EFFECTS OF ALTERING CAMSHAFT TIMING
Advancing Retarding
Begins Intake Event Sooner Delays Intake Closing Event
Open Intake Valve Sooner Keeps Intake Valve Open Later
Builds More Low-End Torque Builds More High-RPM Power
Decrease Piston-Intake Valve Clearance Increase Piston-Intake Valve Clearance
Increase Piston-Exhaust Valve Clearance Decrease 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 Lobe Separation Diagram
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

 

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Last Edited Oct 31st, 2007