Estimating timing chain wear
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In the majority of cases, installing the cam "straight up" (without any advance/retard added by the installer) is the correct way to install the cam and timing set. Many cam makers have already advanced (in most cases) the cam timing when the cam was made, to suit the application. Unless the builder has access to an engine dynamometer or has advanced knowledge of the dynamics involved, advancing/retarding a cam is nothing but a shot in the dark as to whether it will result in any benefits at all. And there's the chance the engine output could be adversely affected by indiscriminately changing the phasing of the cam. | In the majority of cases, installing the cam "straight up" (without any advance/retard added by the installer) is the correct way to install the cam and timing set. Many cam makers have already advanced (in most cases) the cam timing when the cam was made, to suit the application. Unless the builder has access to an engine dynamometer or has advanced knowledge of the dynamics involved, advancing/retarding a cam is nothing but a shot in the dark as to whether it will result in any benefits at all. And there's the chance the engine output could be adversely affected by indiscriminately changing the phasing of the cam. | ||
| + | |||
| + | ==Effects of changing cam timing== | ||
| + | |||
| + | ===Advance timing=== | ||
| + | *Open Intake Valve Sooner | ||
| + | *Builds more low-end torque | ||
| + | *Decreases piston to intake valve clearance | ||
| + | *Increases piston to exhaust valve clearance | ||
| + | |||
| + | ===Retard timing=== | ||
| + | *Keeps intake valve open later | ||
| + | *Builds more upper RPM power | ||
| + | *Increases piston to intake valve clearance | ||
| + | *Decreases piston to exhaust valve clearance | ||
| + | |||
| + | ==Effects of changing lobe separation angle== | ||
| + | The lobe separation angle (LSA) is ground into the cam at the time of manufacture and cannot be changed by the installer. | ||
| + | |||
| + | ===Widen (larger) LSA=== | ||
| + | *Raises torque to higher RPM | ||
| + | *Reduces maximum torque | ||
| + | *Broadens power band | ||
| + | *Reduces maximum cylinder pressure | ||
| + | *Decrease chance of engine knock | ||
| + | *Decrease cranking compression | ||
| + | *Decrease effective compression | ||
| + | *Idle vacuum is increased | ||
| + | *Idle Quality improves | ||
| + | *Overlap decreases | ||
| + | *Natural EGR effect is reduced | ||
| + | *Increases piston-to-valve clearance | ||
| + | |||
| + | ===Tighten (smaller) LSA=== | ||
| + | *Moves torque to lower RPM | ||
| + | *Increases maximum torque | ||
| + | *Narrow power band | ||
| + | *Builds higher cylinder pressure | ||
| + | *Increase chance of engine knock | ||
| + | *Increase cranking compression | ||
| + | *Increase effective compression | ||
| + | *Idle vacuum is reduced | ||
| + | *Idle quality suffers | ||
| + | *Overlap increases | ||
| + | *Natural EGR effect increases | ||
| + | *Decreases piston-to-valve clearance | ||
==Resources== | ==Resources== | ||
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