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- Aug 18, 2008
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What would be a good cam timing arrangement for a 4 cylinder, 1" x 1.25" b x s, throttle governed, constant speed (500-700 RPM) engine that would yield good smooth operation? The flywheel will be plenty heavy.
Although it may not be transferrable to models, I have reviewed early automotive (1912-1950) cam timing and found they almost always opened the intake valves 5 to 17 degrees ATDC, closed 28-50 degrees ABDC. The exhaust valves opened 37-55 degrees BBDC and closed 0-10 degrees ATDC. They all had little, or no valve overlap. However, some stationary engines of the same period operating at 250-550 RPM used up to 18 degrees of overlap. Lobe separations were all about 108-115. The only thing I can see is the relative size differnce of these two type engines. Any thoughts would be appreciated.
Jeff
Although it may not be transferrable to models, I have reviewed early automotive (1912-1950) cam timing and found they almost always opened the intake valves 5 to 17 degrees ATDC, closed 28-50 degrees ABDC. The exhaust valves opened 37-55 degrees BBDC and closed 0-10 degrees ATDC. They all had little, or no valve overlap. However, some stationary engines of the same period operating at 250-550 RPM used up to 18 degrees of overlap. Lobe separations were all about 108-115. The only thing I can see is the relative size differnce of these two type engines. Any thoughts would be appreciated.
Jeff