Dumb question about timing....
02-11-2004, 10:02 AM
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Dumb question about timing.... I dont completely understand timing. I see people saying they have 18* or 22* OR 27* but what does that mean? Can you give me the basics of better understanding timing?
02-11-2004, 10:18 AM
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www.howstuffworks.com
^^ seek engine, fuel injection etc
good newb read on the combustion motor.
18 = degrees, hopefully, BEFORE TOP DEAD CENTER (piston location on power stroke)
^^ seek engine, fuel injection etc
good newb read on the combustion motor.
18 = degrees, hopefully, BEFORE TOP DEAD CENTER (piston location on power stroke)
02-12-2004, 10:31 AM
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As the motor rotates faster, or is placed under less load, you need to "fire" the fuel mixture SOONER (it burns at a constant rate regardless of RPM) so it expands and produces power at the correct time to push the piston back down.
A perfect piston (picture a cannonball in a cannon) is fired at TDC, or at the top of it's travel. But an engine has "cannonballs" that go back and forth, and at different speeds. So that is why you need to change the timing, or the point where the spark plug ignites the mixture, to provide the most power WITHOUT "bucking" the piston - forcing it down when it's still travelling up!. This is pre-ignition, commonly called "knock"; and you can see why it's NOT a good thing!
Actually there are MANY variables to WHEN to ignite the mixture, and that is why computers control the spark, as opposed to the old "weights and springs", which worked, but inefficiently when compared to modern electronic ignitinon systems.
A perfect piston (picture a cannonball in a cannon) is fired at TDC, or at the top of it's travel. But an engine has "cannonballs" that go back and forth, and at different speeds. So that is why you need to change the timing, or the point where the spark plug ignites the mixture, to provide the most power WITHOUT "bucking" the piston - forcing it down when it's still travelling up!. This is pre-ignition, commonly called "knock"; and you can see why it's NOT a good thing!
Actually there are MANY variables to WHEN to ignite the mixture, and that is why computers control the spark, as opposed to the old "weights and springs", which worked, but inefficiently when compared to modern electronic ignitinon systems.
Last edited by emarkay; 02-12-2004 at 10:32 AM. Reason: spelling