Thanks, evolutionmovement.
Probably more than I'll know what to do with, but definitely not more than I wanted to know.
Yesterday, I was reading the web pages in the "Tech Area" of Delta Camshaft's web site (under reconstruction, but parts of it are still up at the moment (but maybe not by the time you click on the following links).
Reading CAMSHAFT TUNING TIPS has me wondering if offset bushing/keys aren't the place to begin?
Quote:
Advancing and Retarding:
By advancing the cam, the valves open and close earlier. Duration and overlap remain unchanged. Advancing raises the cylinder pressure (due to earlier valve closing) This improves low end and mid-range torque at the expense of some top-end power. The result is similar to using a shorter-duration cam since the intake valve closing point is more critical than its opening point.
<snip (retarding = more top end hp)>
Advancing and retarding are easily accomplished with offset bushings or keys for the cam or crankshaft, depending on the engine. The bushings and keys are usually supplied in increments of 2, 4, 6, and 8 crankshaft degrees. Remember that one crankshaft degree equals two camshaft degrees.
How Much is Enough?
Trial and error is usually the best method when advancing or retarding a cam to alter performance. Our experience indicates that cam advance of 2' to 6' should give the best overall performance. These settings have helped top-end power in many engines.
Before attempting to advance or retard a cam, you must know the actual valve timing, not the manufacturer's specifications.
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I'm guessing that the last sentence means the same as their "IMPORTANT NOTES"?
Quote:
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Advancing and retarding a camshaft will move valves closer to the piston. Valve-to-piston clearance must be checked after advancing or retarding alterations to prevent possible engine damage. Also, changing the cam timing will also change ignition timing, which must then be reset.
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