There are dozens of variables that affect the ignition point-compression, valve timing, chamber design, and many others-for optimum ignition advance rates. If your engine turned at about one rpm this process would work, but the piston goes up and down 10 times a second at 600 rpm and 100 times a second at 6000 rpm. When the piston gets to TDC you close the exhaust valve, open the intake valve, and the process starts over. When the piston gets to BDC you open the exhaust valve, and as the piston goes up it pushes the burned gas out the exhaust. This causes the pressure in the cylinder to rise and pushes the piston down. When the piston gets to TDC you fire the spark plug, which lights the mixture in the cylinder. When the piston is at Bottom Dead Center (BDC) you close the intake valve, and, when the piston goes up, it will compress the gas in the cylinder.
When the piston goes down it will pull in a mixture of gas and air. When the piston is at Top Dead Center (TDC) you open the intake valve. What is distributor advance and why should changing it make your car run better? The basic idea is simple.
